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#Underscore Lab

You're going to recreate some of the functionality of the popular JS library Underscore.js. Write all of the following methods inside of an _ object.

Fork this repo, push your code to your fork, and submit the link to your fork on students.gschool

##Part 1

• average - returns the average value in a given array

_.average([4,6,1,1])
=> 3

• contains - returns true is a given value is present in an array

_.contains([7,55,99], 99);
=> true

• first - returns the first element in an array

_.first([5, 4, 3, 2, 1]);
=> 5

• last - returns the last element in an array

_.last([5, 4, 3, 2, 1]);
=> 1

• max - returns the maximum value in an array

var numbers = [10, 5, 100, 2, 1000];
_.max(numbers);
=> 1000

• min - returns the minimum value in an array

var numbers = [10, 5, 100, 2, 1000];
_.min(numbers);
=> 2

• shuffle - Returns a shuffled copy of the list, using a version of the Fisher-Yates shuffle. Don't worry about implementing that exact shuffle alogrithm. Start by creating your own simple shuffle.

_.shuffle([1, 2, 3, 4, 5, 6]);
=> [4, 1, 6, 3, 5, 2]

• sample - Produce a random sample from the list. Pass a number to return n random elements from the list. Otherwise a single random item will be returned.

_.sample([1, 2, 3, 4, 5, 6]);
=> 4

_.sample([1, 2, 3, 4, 5, 6], 3);
=> [1, 6, 2]

• difference - returns the values from array that are not present in the other array.

_.difference([1, 2, 3, 4, 5], [5, 2, 10]);
=> [1, 3, 4]

• indexOf - Returns the index at which value can be found in the array, or -1 if value is not present in the array.

_.indexOf([1, 2, 3], 2);
=> 1

• pluck - extracts a list of property values and returns them in an array.

  var stooges = [{name: 'moe', age: 40}, {name: 'larry', age: 50}, {name: 'curly', age: 60}];
_.pluck(stooges, 'name');
=> ["moe", "larry", "curly"]

##Part 2

• each - iterates over an array and calls a given function with each element

_.each([1, 2, 3], alert);
=> alerts each number in turn...

• compact - returns a new array with all provided undefined values removed

_.compact([1, "hello", undefined, 3, undefined]);
=> [1, "hello", 3]

• map - returns a new array of values produced by running each element of an array through a given function

_.map([1, 2, 3], function(num){ return num * 3; });
=> [3, 6, 9]

_.map(["dogs", "before", "cats"], function(str){ return str.toUpperCase(); });
=> ["DOGS", "BEFORE", "CATS"]

• filter - Looks through each value in the list, returning an array of all the values that pass a truth test

var evens = _.filter([1, 2, 3, 4, 5, 6], function(num){ return num % 2 == 0; });
=> [2, 4, 6]