This will eventually be a project we can clone and use to start a new mofo-opinionated app, so let's have it implement the assertions from #16

• Acquire private key, cert, intermediate
• Share in lastpass with DevOps
• Add cert to mofosecure instance for EC2
• Add cert to mofosecure cloudfront
• Document cert usage in mofosecure documentation

Airbnb JavaScript Style Guide() {

A mostly reasonable approach to JavaScript

Table of Contents

1. Types
2. undefined
3. Objects
4. Arrays
5. Strings
6. Functions
7. Properties
8. Variables
9. Hoisting
10. Conditional Expressions & Equality
11. Blocks
12. Comments
13. Whitespace
14. Commas
15. Semicolons
16. Type Casting & Coercion
17. Naming Conventions
18. Accessors
19. Constructors
20. Events
21. Modules
22. jQuery
23. ECMAScript 5 Compatibility
24. Testing
25. Performance
26. Resources
27. In the Wild
28. Translation
29. The JavaScript Style Guide Guide
30. Contributors
31. License

Types

• Primitives: When you access a primitive type you work directly on its value

  • string
  • number
  • boolean
  • null
  • undefined

  var foo = 1;
  var bar = foo;
  
  bar = 9;
  
  console.log(foo, bar); // => 1, 9

• Complex: When you access a complex type you work on a reference to its value

  • object
  • array
  • function

  var foo = [1, 2];
  var bar = foo;
  
  bar[0] = 9;
  
  console.log(foo[0], bar[0]); // => 9, 9

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undefined

• undefined is an object. You should use it as an object. You can test for it. For instance:

  // good
  function pow(a, b) {
    if (b === undefined) {
      b = 1;
    }
    return Math.pow(a, b);
  }
  
  // bad
  function pow(a, b) {
    if (typeof b == "undefined") {
      b = 1;
    }
    return Math.pow(a, b);
  }

• Only use typeof x == "undefined" when the variable (x) may not be declared, and it would be an error to test x === undefined:

  if (typeof Module == "undefined") {
    Module = {};
  }
  
  // But also okay, for browser-only code:
  if (window.Module === undefined) {
    Module = {};
  }

  Note that you can't use window in Node.js; if you think your code could be used in a server context you should use the first form.

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Objects

• Use the literal syntax for object creation.

  // bad
  var item = new Object();
  
  // good
  var item = {};

  if (typeof Module == "undefined") {
    Module = {};
  }
  
  // But also okay, for browser-only code:
  if (window.Module === undefined) {
    Module = {};
  }

  Note that you can't use window in Node.js; if you think your code could be used in a server context you should use the first form.

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Objects

• Use the literal syntax for object creation.

  // bad
  var item = new Object();
  
  // good
  var item = {};

  • You may use reserved words as keys.

  As an example that reserved words are both okay right now and will be indefinitely, the IndexedDB API uses cursor.continue()

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Arrays

• Use the literal syntax for array creation

  // bad
  var items = new Array();
  
  // good
  var items = [];

• If you don't know array length use Array#push.

  var someStack = [];
  
  
  // bad
  someStack[someStack.length] = 'abracadabra';
  
  // good
  someStack.push('abracadabra');

• When you need to copy an array use Array#slice. jsPerf

  var len = items.length;
  var itemsCopy = [];
  var i;
  
  // bad
  for (i = 0; i < len; i++) {
    itemsCopy[i] = items[i];
  }
  
  // good
  itemsCopy = items.slice();

• To convert an array-like object to an array, use Array#slice.

  function trigger() {
    var args = Array.prototype.slice.call(arguments);
    ...
  }

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Strings

• Use single or double quotes (' or ") for strings. There is a slight preference for double-quotes, aligning with Mozilla style.

• Strings longer than 80 characters should be written across multiple lines using string concatenation.

• Note: If overused, long strings with concatenation could impact performance. jsPerf & Discussion

  // bad
  var errorMessage = 'This is a super long error that was thrown because of Batman. When you stop to think about how Batman had anything to do with this, you would get nowhere fast.';
  
  // bad
  var errorMessage = 'This is a super long error that was thrown because \
  of Batman. When you stop to think about how Batman had anything to do \
  with this, you would get nowhere \
  fast.';
  
  // good
  var errorMessage = 'This is a super long error that was thrown because ' +
    'of Batman. When you stop to think about how Batman had anything to do ' +
    'with this, you would get nowhere fast.';

• When programmatically building up a string, use Array#join instead of string concatenation. Mostly for IE: jsPerf.

  var items;
  var messages;
  var length;
  var i;
  
  messages = [{
    state: 'success',
    message: 'This one worked.'
  }, {
    state: 'success',
    message: 'This one worked as well.'
  }, {
    state: 'error',
    message: 'This one did not work.'
  }];
  
  length = messages.length;
  
  // bad
  function inbox(messages) {
    items = '<ul>';
  
    for (i = 0; i < length; i++) {
      items += '<li>' + messages[i].message + '</li>';
    }
  
    return items + '</ul>';
  }
  
  // good
  function inbox(messages) {
    items = [];
  
    for (i = 0; i < length; i++) {
      items[i] = messages[i].message;
    }
  
    return '<ul><li>' + items.join('</li><li>') + '</li></ul>';
  }

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Functions

• Function expressions:

  // anonymous function expression
  var anonymous = function() {
    return true;
  };
  
  // named function expression
  var named = function named() {
    return true;
  };
  
  // immediately-invoked function expression (IIFE)
  (function() {
    console.log('Welcome to the Internet. Please follow me.');
  })();

• Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad news bears.

• Note: ECMA-262 defines a block as a list of statements. A function declaration is not a statement. Read ECMA-262's note on this issue.

  // bad
  if (currentUser) {
    function test() {
      console.log('Nope.');
    }
  }
  
  // good
  var test;
  if (currentUser) {
    test = function test() {
      console.log('Yup.');
    };
  }

• Never name a parameter arguments, this will take precedence over the arguments object that is given to every function scope.

  // bad
  function nope(name, options, arguments) {
    // ...stuff...
  }
  
  // good
  function yup(name, options, args) {
    // ...stuff...
  }

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Properties

• Use dot notation when accessing properties.

  var luke = {
    jedi: true,
    age: 28
  };
  
  // bad
  var isJedi = luke['jedi'];
  
  // good
  var isJedi = luke.jedi;

• Use subscript notation [] when accessing properties with a variable.

  var luke = {
    jedi: true,
    age: 28
  };
  
  function getProp(prop) {
    return luke[prop];
  }
  
  var isJedi = getProp('jedi');

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Variables

• Always use var to declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. Captain Planet warned us of that.

  // bad
  superPower = new SuperPower();
  
  // good
  var superPower = new SuperPower();

• Use one var declaration per variable and declare each variable on a newline.

  // bad
  var items = getItems(),
      goSportsTeam = true,
      dragonball = 'z';
  
  // good
  var items = getItems();
  var goSportsTeam = true;
  var dragonball = 'z';

• Assign variables at the top of their scope. This helps avoid issues with variable declaration and assignment hoisting related issues.

  // bad
  function() {
    test();
    console.log('doing stuff..');
  
    //..other stuff..
  
    var name = getName();
  
    if (name === 'test') {
      return false;
    }
  
    return name;
  }
  
  // good
  function() {
    var name = getName();
  
    test();
    console.log('doing stuff..');
  
    //..other stuff..
  
    if (name === 'test') {
      return false;
    }
  
    return name;
  }
  
  // bad
  function() {
    var name = getName();
  
    if (!arguments.length) {
      return false;
    }
  
    return true;
  }
  
  // good
  function() {
    if (!arguments.length) {
      return false;
    }
  
    var name = getName();
  
    return true;
  }

• As an exception, declaring a variable in a for loop is common and okay.

  // ok
  for (var i=0; i<array.length; i++) {
    ...
  }

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Hoisting

• Variable declarations get hoisted to the top of their scope, their assignment does not.

  // we know this wouldn't work (assuming there
  // is no notDefined global variable)
  function example() {
    console.log(notDefined); // => throws a ReferenceError
  }
  
  // creating a variable declaration after you
  // reference the variable will work due to
  // variable hoisting. Note: the assignment
  // value of `true` is not hoisted.
  function example() {
    console.log(declaredButNotAssigned); // => undefined
    var declaredButNotAssigned = true;
  }
  
  // The interpreter is hoisting the variable
  // declaration to the top of the scope.
  // Which means our example could be rewritten as:
  function example() {
    var declaredButNotAssigned;
    console.log(declaredButNotAssigned); // => undefined
    declaredButNotAssigned = true;
  }

• Anonymous function expressions hoist their variable name, but not the function assignment.

  function example() {
    console.log(anonymous); // => undefined
  
    anonymous(); // => TypeError anonymous is not a function
  
    var anonymous = function() {
      console.log('anonymous function expression');
    };
  }

• Named function expressions hoist the variable name, not the function name or the function body.

  function example() {
    console.log(named); // => undefined
  
    named(); // => TypeError named is not a function
  
    superPower(); // => ReferenceError superPower is not defined
  
    var named = function superPower() {
      console.log('Flying');
    };
  }
  
  // the same is true when the function name
  // is the same as the variable name.
  function example() {
    console.log(named); // => undefined
  
    named(); // => TypeError named is not a function
  
    var named = function named() {
      console.log('named');
    }
  }

• Function declarations hoist their name and the function body.

  function example() {
    superPower(); // => Flying
  
    function superPower() {
      console.log('Flying');
    }
  }

• For more information refer to JavaScript Scoping & Hoisting by Ben Cherry

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Conditional Expressions & Equality

• Use === and !== over == and !=.

• Conditional expressions are evaluated using coercion with the ToBoolean method and always follow these simple rules:

  • Objects evaluate to true
  • Undefined evaluates to false
  • Null evaluates to false
  • Booleans evaluate to the value of the boolean
  • Numbers evaluate to false if +0, -0, or NaN, otherwise true
  • Strings evaluate to false if an empty string '', otherwise true

  if ([0]) {
    // true
    // An array is an object, objects evaluate to true
  }

• Use shortcuts.

  // bad
  if (name !== '') {
    // ...stuff...
  }
  
  // good
  if (name) {
    // ...stuff...
  }
  
  // bad
  if (collection.length > 0) {
    // ...stuff...
  }
  
  // good
  if (collection.length) {
    // ...stuff...
  }

• For more information see Truth Equality and JavaScript by Angus Croll

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Blocks

• Use braces with all multi-line blocks.

  // bad
  if (test)
    return false;
  
  // good
  if (test) return false;
  
  // good
  if (test) {
    return false;
  }
  
  // bad
  function() { return false; }
  
  // good
  function() {
    return false;
  }

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Comments

• Use /** ... */ for multiline comments. Include a description, specify types and values for all parameters and return values.

  // bad
  // make() returns a new element
  // based on the passed in tag name
  //
  // @param <String> tag
  // @return <Element> element
  function make(tag) {
  
    // ...stuff...
  
    return element;
  }
  
  // good
  /**
   * make() returns a new element
   * based on the passed in tag name
   *
   * @param <String> tag
   * @return <Element> element
   */
  function make(tag) {
  
    // ...stuff...
  
    return element;
  }

• Use // for single line comments. Place single line comments on a newline above the subject of the comment. Put an empty line before the comment.

  // bad
  var active = true;  // is current tab
  
  // good
  // is current tab
  var active = true;
  
  // bad
  function getType() {
    console.log('fetching type...');
    // set the default type to 'no type'
    var type = this._type || 'no type';
  
    return type;
  }
  
  // good
  function getType() {
    console.log('fetching type...');
  
    // set the default type to 'no type'
    var type = this._type || 'no type';
  
    return type;
  }

• Prefixing your comments with FIXME or TODO helps other developers quickly understand if you're pointing out a problem that needs to be revisited, or if you're suggesting a solution to the problem that needs to be implemented. These are different than regular comments because they are actionable. The actions are FIXME -- need to figure this out or TODO -- need to implement.

• Use // FIXME: to annotate problems

  function Calculator() {
  
    // FIXME: shouldn't use a global here
    total = 0;
  
    return this;
  }

• Use // TODO: to annotate solutions to problems

  function Calculator() {
  
    // TODO: total should be configurable by an options param
    this.total = 0;
  
    return this;
  }

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Whitespace

• Use soft tabs set to 2 spaces

  // bad
  function() {
  ∙∙∙∙var name;
  }
  
  // bad
  function() {
  ∙var name;
  }
  
  // good
  function() {
  ∙∙var name;
  }

• Place 1 space before the leading brace.

  // bad
  function test(){
    console.log('test');
  }
  
  // good
  function test() {
    console.log('test');
  }
  
  // bad
  dog.set('attr',{
    age: '1 year',
    breed: 'Bernese Mountain Dog'
  });
  
  // good
  dog.set('attr', {
    age: '1 year',
    breed: 'Bernese Mountain Dog'
  });

• Set off operators with spaces.

  // bad
  var x=y+5;
  
  // good
  var x = y + 5;

• End files with a single newline character.

  // bad
  (function(global) {
    // ...stuff...
  })(this);

  // bad
  (function(global) {
    // ...stuff...
  })(this);↵
  ↵

  // good
  (function(global) {
    // ...stuff...
  })(this);↵

• Use indentation when making long method chains.

  // bad
  $('#items').find('.selected').highlight().end().find('.open').updateCount();
  
  // good
  $('#items')
    .find('.selected')
      .highlight()
      .end()
    .find('.open')
      .updateCount();
  
  // bad
  var leds = stage.selectAll('.led').data(data).enter().append('svg:svg').class('led', true)
      .attr('width',  (radius + margin) * 2).append('svg:g')
      .attr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')')
      .call(tron.led);
  
  // good
  var leds = stage.selectAll('.led')
      .data(data)
    .enter().append('svg:svg')
      .class('led', true)
      .attr('width',  (radius + margin) * 2)
    .append('svg:g')
      .attr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')')
      .call(tron.led);

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Commas

• Leading commas: Nope.

  // bad
  var hero = {
      firstName: 'Bob'
    , lastName: 'Parr'
    , heroName: 'Mr. Incredible'
    , superPower: 'strength'
  };
  
  // good
  var hero = {
    firstName: 'Bob',
    lastName: 'Parr',
    heroName: 'Mr. Incredible',
    superPower: 'strength'
  };

• Additional trailing comma: Nope. This can cause problems with IE6/7 and IE9 if it's in quirksmode. Also, in some implementations of ES3 would add length to an array if it had an additional trailing comma. This was clarified in ES5 (source):

  Edition 5 clarifies the fact that a trailing comma at the end of an ArrayInitialiser does not add to the length of the array. This is not a semantic change from Edition 3 but some implementations may have previously misinterpreted this.

    // bad
    var hero = {
      firstName: 'Kevin',
      lastName: 'Flynn',
    };
  
    var heroes = [
      'Batman',
      'Superman',
    ];
  
    // good
    var hero = {
      firstName: 'Kevin',
      lastName: 'Flynn'
    };
  
    var heroes = [
      'Batman',
      'Superman'
    ];

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Semicolons

• Yup.

  // bad
  (function() {
    var name = 'Skywalker'
    return name
  })()
  
  // good
  (function() {
    var name = 'Skywalker';
    return name;
  })();
  
  // good (guards against the function becoming an argument when two files with IIFEs are concatenated)
  ;(function() {
    var name = 'Skywalker';
    return name;
  })();

  Read more.

⬆ back to top

Type Casting & Coercion

• Perform type coercion at the beginning of the statement.

• Strings:

  //  => this.reviewScore = 9;
  
  // bad
  var totalScore = this.reviewScore + '';
  
  // good
  var totalScore = '' + this.reviewScore;
  
  // bad
  var totalScore = '' + this.reviewScore + ' total score';
  
  // good
  var totalScore = this.reviewScore + ' total score';

• Use parseInt for Numbers and always with a radix for type casting.

  var inputValue = '4';
  
  // bad
  var val = new Number(inputValue);
  
  // bad
  var val = +inputValue;
  
  // bad
  var val = inputValue >> 0;
  
  // bad
  var val = parseInt(inputValue);
  
  // good
  var val = Number(inputValue);
  
  // good
  var val = parseInt(inputValue, 10);

• If for whatever reason you are doing something wild and parseInt is your bottleneck and need to use Bitshift for performance reasons, leave a comment explaining why and what you're doing.

  // good
  /**
   * parseInt was the reason my code was slow.
   * Bitshifting the String to coerce it to a
   * Number made it a lot faster.
   */
  var val = inputValue >> 0;

• Note: Be careful when using bitshift operations. Numbers are represented as 64-bit values, but Bitshift operations always return a 32-bit integer (source). Bitshift can lead to unexpected behavior for integer values larger than 32 bits. Discussion. Largest signed 32-bit Int is 2,147,483,647:

  2147483647 >> 0 //=> 2147483647
  2147483648 >> 0 //=> -2147483648
  2147483649 >> 0 //=> -2147483647

• Booleans:

  var age = 0;
  
  // bad
  var hasAge = new Boolean(age);
  
  // good
  var hasAge = Boolean(age);
  
  // good
  var hasAge = !!age;

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Naming Conventions

• Avoid single letter names. Be descriptive with your naming.

  // bad
  function q() {
    // ...stuff...
  }
  
  // good
  function query() {
    // ..stuff..
  }

• Use camelCase when naming objects, functions, and instances

  // bad
  var OBJEcttsssss = {};
  var this_is_my_object = {};
  function c() {}
  var u = new user({
    name: 'Bob Parr'
  });
  
  // good
  var thisIsMyObject = {};
  function thisIsMyFunction() {}
  var user = new User({
    name: 'Bob Parr'
  });

• Use PascalCase when naming constructors or classes

  // bad
  function user(options) {
    this.name = options.name;
  }
  
  var bad = new user({
    name: 'nope'
  });
  
  // good
  function User(options) {
    this.name = options.name;
  }
  
  var good = new User({
    name: 'yup'
  });

• When saving a reference to this use self.

  // bad
  function() {
    var _this = this;
    return function() {
      console.log(_this);
    };
  }
  
  // good
  function() {
    var self = this;
    return function() {
      console.log(self);
    };
  }

• Name your functions. This is helpful for stack traces.

  // bad
  var log = function(msg) {
    console.log(msg);
  };
  
  // good
  var log = function log(msg) {
    console.log(msg);
  };

• Note: IE8 and below exhibit some quirks with named function expressions. See http://kangax.github.io/nfe/ for more info.

⬆ back to top

Accessors

• Accessor functions for properties are not required

• If the property is a boolean, use isVal() or hasVal()

  // bad
  if (!dragon.age()) {
    return false;
  }
  
  // good
  if (!dragon.hasAge()) {
    return false;
  }

• It's okay to create get() and set() functions, but be consistent.

  function Jedi(options) {
    options || (options = {});
    var lightsaber = options.lightsaber || 'blue';
    this.set('lightsaber', lightsaber);
  }
  
  Jedi.prototype.set = function(key, val) {
    this[key] = val;
  };
  
  Jedi.prototype.get = function(key) {
    return this[key];
  };

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Constructors

• Assign methods to the prototype object, instead of overwriting the prototype with a new object. Overwriting the prototype makes inheritance impossible: by resetting the prototype you'll overwrite the base!

  function Jedi() {
    console.log('new jedi');
  }
  
  // bad
  Jedi.prototype = {
    fight: function fight() {
      console.log('fighting');
    },
  
    block: function block() {
      console.log('blocking');
    }
  };
  
  // good
  Jedi.prototype.fight = function fight() {
    console.log('fighting');
  };
  
  Jedi.prototype.block = function block() {
    console.log('blocking');
  };

• Methods can return this to help with method chaining.

  // bad
  Jedi.prototype.jump = function() {
    this.jumping = true;
    return true;
  };
  
  Jedi.prototype.setHeight = function(height) {
    this.height = height;
  };
  
  var luke = new Jedi();
  luke.jump(); // => true
  luke.setHeight(20) // => undefined
  
  // good
  Jedi.prototype.jump = function() {
    this.jumping = true;
    return this;
  };
  
  Jedi.prototype.setHeight = function(height) {
    this.height = height;
    return this;
  };
  
  var luke = new Jedi();
  
  luke.jump()
    .setHeight(20);

• It's okay to write a custom toString() method, just make sure it works successfully and causes no side effects.

  function Jedi(options) {
    options || (options = {});
    this.name = options.name || 'no name';
  }
  
  Jedi.prototype.getName = function getName() {
    return this.name;
  };
  
  Jedi.prototype.toString = function toString() {
    return 'Jedi - ' + this.getName();
  };

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Events

• When attaching data payloads to events (whether DOM events or something more proprietary like Backbone events), pass a hash instead of a raw value. This allows a subsequent contributor to add more data to the event payload without finding and updating every handler for the event. For example, instead of:

  // bad
  $(this).trigger('listingUpdated', listing.id);
  
  ...
  
  $(this).on('listingUpdated', function(e, listingId) {
    // do something with listingId
  });

  prefer:

  // good
  $(this).trigger('listingUpdated', { listingId : listing.id });
  
  ...
  
  $(this).on('listingUpdated', function(e, data) {
    // do something with data.listingId
  });

  ⬆ back to top

Modules

• The module should start with a !. This ensures that if a malformed module forgets to include a final semicolon there aren't errors in production when the scripts get concatenated. Explanation

• The file should be named with camelCase, live in a folder with the same name, and match the name of the single export.

• Add a method called noConflict() that sets the exported module to the previous version and returns this one.

• Always declare 'use strict'; at the top of the module.

  // fancyInput/fancyInput.js
  
  !function(global) {
    'use strict';
  
    var previousFancyInput = global.FancyInput;
  
    function FancyInput(options) {
      this.options = options || {};
    }
  
    FancyInput.noConflict = function noConflict() {
      global.FancyInput = previousFancyInput;
      return FancyInput;
    };
  
    global.FancyInput = FancyInput;
  }(this);

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jQuery

• Cache jQuery lookups.

  // bad
  function setSidebar() {
    $('.sidebar').hide();
  
    // ...stuff...
  
    $('.sidebar').css({
      'background-color': 'pink'
    });
  }
  
  // good
  function setSidebar() {
    var $sidebar = $('.sidebar');
    $sidebar.hide();
  
    // ...stuff...
  
    $sidebar.css({
      'background-color': 'pink'
    });
  }

• For DOM queries use Cascading $('.sidebar ul') or parent > child $('.sidebar > ul'). jsPerf

• Use find with scoped jQuery object queries.

  // bad
  $('ul', '.sidebar').hide();
  
  // bad
  $('.sidebar').find('ul').hide();
  
  // good
  $('.sidebar ul').hide();
  
  // good
  $('.sidebar > ul').hide();
  
  // good
  $sidebar.find('ul').hide();

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ECMAScript 5 Compatibility

• Refer to Kangax's ES5 compatibility table

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Testing

• Yup.

  function() {
    return true;
  }

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Performance

• On Layout & Web Performance
• String vs Array Concat
• Try/Catch Cost In a Loop
• Bang Function
• jQuery Find vs Context, Selector
• innerHTML vs textContent for script text
• Long String Concatenation
• Loading...

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Resources

Read This

• Annotated ECMAScript 5.1

Other Styleguides

• Google JavaScript Style Guide
• jQuery Core Style Guidelines
• Principles of Writing Consistent, Idiomatic JavaScript

Other Styles

• Naming this in nested functions - Christian Johansen
• Conditional Callbacks
• Popular JavaScript Coding Conventions on Github

Further Reading

• Understanding JavaScript Closures - Angus Croll
• Basic JavaScript for the impatient programmer - Dr. Axel Rauschmayer
• You Might Not Need jQuery - Zack Bloom & Adam Schwartz
• ES6 Features - Luke Hoban

Books

• JavaScript: The Good Parts - Douglas Crockford
• JavaScript Patterns - Stoyan Stefanov
• Pro JavaScript Design Patterns - Ross Harmes and Dustin Diaz
• High Performance Web Sites: Essential Knowledge for Front-End Engineers - Steve Souders
• Maintainable JavaScript - Nicholas C. Zakas
• JavaScript Web Applications - Alex MacCaw
• Pro JavaScript Techniques - John Resig
• Smashing Node.js: JavaScript Everywhere - Guillermo Rauch
• Secrets of the JavaScript Ninja - John Resig and Bear Bibeault
• Human JavaScript - Henrik Joreteg
• Superhero.js - Kim Joar Bekkelund, Mads Mobæk, & Olav Bjorkoy
• JSBooks
• Third Party JavaScript - Ben Vinegar and Anton Kovalyov

Blogs

• DailyJS
• JavaScript Weekly
• JavaScript, JavaScript...
• Bocoup Weblog
• Adequately Good
• NCZOnline
• Perfection Kills
• Ben Alman
• Dmitry Baranovskiy
• Dustin Diaz
• nettuts

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In the Wild

This is a list of organizations that are using this style guide. Send us a pull request or open an issue and we'll add you to the list.

• Aan Zee: AanZee/javascript
• Airbnb: airbnb/javascript
• American Insitutes for Research: AIRAST/javascript
• Compass Learning: compasslearning/javascript-style-guide
• DailyMotion: dailymotion/javascript
• Digitpaint digitpaint/javascript
• ExactTarget: ExactTarget/javascript
• Gawker Media: gawkermedia/javascript
• GeneralElectric: GeneralElectric/javascript
• GoodData: gooddata/gdc-js-style
• Grooveshark: grooveshark/javascript
• How About We: howaboutwe/javascript
• Mighty Spring: mightyspring/javascript
• MinnPost: MinnPost/javascript
• ModCloth: modcloth/javascript
• Money Advice Service: moneyadviceservice/javascript
• Muber: muber/javascript
• National Geographic: natgeo/javascript
• National Park Service: nationalparkservice/javascript
• Orion Health: orionhealth/javascript
• Peerby: Peerby/javascript
• Razorfish: razorfish/javascript-style-guide
• reddit: reddit/styleguide/javascript
• REI: reidev/js-style-guide
• Ripple: ripple/javascript-style-guide
• SeekingAlpha: seekingalpha/javascript-style-guide
• Shutterfly: shutterfly/javascript
• TheLadders: TheLadders/javascript
• Userify: userify/javascript
• Zillow: zillow/javascript
• ZocDoc: ZocDoc/javascript

Translation

This style guide is also available in other languages:

• 🇩🇪 German: timofurrer/javascript-style-guide
• 🇯🇵 Japanese: mitsuruog/javacript-style-guide
• :br: Portuguese: armoucar/javascript-style-guide
• 🇨🇳 Chinese: adamlu/javascript-style-guide
• 🇪🇸 Spanish: paolocarrasco/javascript-style-guide
• 🇰🇷 Korean: tipjs/javascript-style-guide
• 🇫🇷 French: nmussy/javascript-style-guide
• 🇷🇺 Russian: uprock/javascript
• :bg: Bulgarian: borislavvv/javascript

The JavaScript Style Guide Guide

• Reference

Contributors

• View Contributors

License

(The MIT License)

Copyright (c) 2014 Airbnb

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

⬆ back to top

};

We should have better guidelines around Accessibility. Let's do it!

We need to codify best practices for writing UI components that are reusable across all our codebases and stack variants.

ES6 is becoming more practical pretty quickly, especially thanks to transpilers and things like sweet.js.

See http://glenmaddern.com/articles/javascript-in-2015 for an example of what that feels like. See also io.js if we wanted to be bleeding-edge on the server side.

My guess is we don't want to be early adopters just yet, but it's worth a conversation.

• Tell JP what kind of server/infrastructure you need. Presumably just an S3 bucket fronted by CF with SSL?
• Create form, get it ready for hosting
• Coordinate with JP to get form hosted in new S3 bucket, DNS set
• Test form against paypal

Coming out of https://docs.google.com/document/d/1BZVJYo3ELxDAcIyU5y_1ScjMtxBYegp5k9gc2rH0kgQ, this needs:

• stubbing a playbook file
• document pre-steps
  • determine whether this playbook applies (2 EFT sprints worth of work? figure this out)
  • create a dedicated slack channel, to be removed after completion
  • how to "spike" (i.e. "investigative work to figure out all the tasks needed for completion")
  • establish the delivery deadline, and deliverables
  • establish the cutoff deadline, and its deliverables (if not met, this means we cannot mean the delivery deadline)
  • establish the length of the follow-up period?
  • how to file all issues
  • how to set up a roadmap/timeline (github project "kanban"?)
  • who's driving, who's helping, who coordinates/signs off on delivery
  • ...

http://nvie.com/posts/a-successful-git-branching-model/

For setup of new users, it would be helpful to have a checklist of github groups, repos, and orgs we add folks to.

• use a JSON response standard such as jsonapi.org

(will fill out more later)

Front-end

Goal: Create a mostly "offline" experience by aggregating project modifications and only saving these to the database at specific times, firing off all operations as an ordered batch update

Original Solution:

Implement java-side object caching (mozilla/webmaker-android#2414) so that edits can be made to pages and elements without needing to synchronize with the database every time a webview is swapped in or out.

Rather than syncing with the database, objects that need to be shared between multiple webviews (effectively: different React applications running in different "tabs") can be cached to java when one view swaps out, and then be retrieved from cache when another view is swapped in, bypassing the need for an external database until the user leaves the page view, at which point all pending modifications for that page get synchronised with the database using a single HTTP call that contains a batch of sequential updates.

This touches quite a few aspects of the code, documented in https://github.com/mozilla/webmaker-core/wiki/Mostly-offline-java-caching-diagrams but summarized here:

• updates to page.jsx to cache to-be-edited elements, as well as link elements for which "set destination" was clicked,
• updates to element.jsx to retrieve to-edit elements from cache, and recache after edits are complete, when entering tinker mode, or when triggering a "set destination" action for link elements,
• updates to tinker.jsx to retrieve the in-edit element from cache and recache it once edits are complete
• updates to project.jsx to retrieve link element information from cache, commit link destination information once the user picks a page as destination, and recache when that choice is committed

With this in place, modifications need only be synchronized with the database when a page view is exited. This is, in fact, still an incomplete solution, and the modifications that are necessary to make this synchronisation only occur when a project is considered "done" (or needing to be saved by the user) have not yet been put in place, instead having been scheduled as follow up (mozilla/webmaker-core#452, with mozilla/webmaker-core#451 as a clean-up followup)

Problems encountered:

• There are a lot of view changes, almost all of which were discovered as the code got updated to take advantage of java-side caching. We have no architecture or application logic documentation that allowed a quick inventory of how many parts of the code would be involved, and how much work would be needed in each place.
• The changes span three repositories, which made getting up and running for testing code changes a challenge, as well as keeping all three in sync as work progress independently on each repository.
• Fully syncing code is relatively clean, fully offline should be relatively clean, but working with a progressively more offline combination of the two made it hard to write code that worked well enough to test without constantly revealing new places things were now broken. Which we ran into a lot.
• Working on a branch is like going on vacation: when you're done, someone may have remodeled your house. Or if your house is on github street, landed many changes that necessitate rebase upon rebase, slowing down the process. Sometimes this is unavoidable, but then everyone should be okay with what is effectively a code freeze, or at least a chill, if not a full freeze.
• We have no automated testing in place to take some of the burden off our hands and move it to CI or even local testing

Retrospective:

• A preliminary code audit to determine what would need to change, with team feedback on that list to figure out all the fine details.
• Architecture and application logic documentation (as boring as diagrams are, they are extremely valuable to see where things happen, involving which other parts of the code)
• Noting that this was bigger than expected on day 3, and calling a mofo-eng council meeting to discuss what to do.
  • https://scifiinterfaces.files.wordpress.com/2015/06/avengers-shadowy-videoconference02.png ?
  • maybe http://img4.wikia.nocookie.net/__cb20130202031305/starwars/images/8/8c/Jedi_Council_RotS.png
  • we can be shadowy and not evil
    • yo no comprendo señor...

API

Goal: Support front-end requirements to limit network requests to a minimum

Original Solution:

Given an array of actions, reduce into an array of results
http://git.io/vOX0w && http://bit.ly/1M5h5AO

• Begin a database transaction (http://git.io/vOX0e)
  • iterate over the keys of the action, to determine if values need to be resolved using values from previously processed actions (http://git.io/vOXEZ && http://git.io/vOXE1)
    • if an error occurs, rollback the transaction, return details of the error
  • select the appropriate stored query to execute for the current action (http://git.io/vOXuZ)
  • format the values to pass into the query (http://git.io/vOXu2)
  • gather the "lookup" values required to validate action permissions (http://git.io/vOXzT)
  • Determine if auth'd user has permission to execute the current action
    • if the action is a create action, continue (http://git.io/vOXzG)
    • if the action depends on a previously created resource in the transaction, continue (http://git.io/vOXzu && http://git.io/vOXgG)
    • if the action depends on a resource that is not part of this transaction, use the lookup values to find it and validate permissions (http://git.io/vOXgK)
      • if not allowed, rollback the transaction.
  • If allowed, execute the query with the values (http://git.io/vOXgQ)
    • If there's an error, rollback
  • format the results from the query (http://git.io/vOXgj)
  • push the raw query results and formatted results onto the reduced result array, and return it to the reduce function for the next iteration (http://git.io/vOX2c)
  • Once finished reducing the actions array into a results array, commit the transaction (http://git.io/vOX2y)
  • analyze the actions done and create a series of cache invalidation tails appropriate for the actions done.
  • http://hapijs.com/api#requesttailname
  • http://git.io/vOXaf && http://git.io/vOXas
  • return the array of formatted results to the client (http://git.io/vOXa6)

(I tried to do the nested list justice in MD, but I think I failed. This further illustrates some of the problems outlined below) - Simon

Problems:

• very nesty
• heavy reliance on scoped variables, making it hard to refactor/maintain
• plentiful amounts of redundancy abounds redundantly

I'd like to have a running record indicating anytime we fail over, and for how long.

• WebSec #9
• Mobile first #15
• Front-end Monitoring, instrumentation & Metrics - Adam
• Webmaker Dev environment #5
• Quality Assurance with People #10
• Automated Testing - #8 Atul
• Pre-flight checklist #4
• Code Reviews #7 - Atul
• Framework choices #16
• How we build content sites #8
• How we do Localization - Scott #11
• Offline - Ali #19
• Writing Software for Expensive and Low-bandwidth Users #14
• User Testing #6
• How we use Github Issues - Simon
• Our JavaScript Style Guide #13

• Verify this is something moco IT can do. Requirements: 60s or lower ttl, health check with < 30 second resolution, ability to handout new cnames and switch back.
• File bug to have this happen or delegate DNS to AWS R53
• Get new address of mofosecure hosted transparent redirecting form
• Setup a failover record for this
• Test the setup
• Communicate diagram of flow.

So there's also a MoFo-Design-Handbook, and I thought it might be cool to have a chapter that's shared between both handbooks on how designers and engineers can successfully collaborate.

Alternatively, the design handbook could have a chapter on working with engineers, and the engineering handbook could have a chapter on working with designers.

I've already filed this same ticket as MozillaFoundation/Design#11, so if you have thoughts on this, please post them there instead.

We should describe where and how we communicate so our community can join our party.

Things to cover:

• Mailing lists
• IRC channels
• Public calendar (for demos etc)
• Public links to Vidyo rooms

Advice i got from @dmose was to do so before the app got too complex. Probably worth @Pomax or someone getting a bit familiar w/ it.

Requirements:

• Must perform on low-end FFOS devices
• Must be under active, significant development
• Must work with browserify + npm + gulp
• Must do well both on touch devices and old skool websites
• Must be compatible with cordova
• Must work very well offline

Thoughts

A fair evaluation may require we see how hard it is to make an actual app with these things. A "todo" app or stress test app is likely not reflective of how we're going to end up actually using whatever choice we settle on.

Up for consideration:

• React
• Polymer

• Quality sign-off