Write a function that greets the user by name, or by saying "Hello, World!" if no name is given.

"Hello, World!" is the traditional first program for beginning programming in a new language.

Note: You can skip this exercise by running:

exercism skip $TRACK_ID hello-world

Write a Hello World! function that can greet someone given their name. The function should return the appropriate greeting.

For an input of "Alice", the response should be "Hello, Alice!".

If a name is not given, the response should be "Hello, World!"

As programmers mature, they eventually want to test their code.

Here at Exercism we simulate Test-Driven Development (TDD), where you write your tests before writing any functionality. The simulation comes in the form of a pre-written test suite, which will signal that you have solved the problem.

It will also provide you with a safety net to explore other solutions without breaking the functionality.

1. Run the test file and pick one test that's failing.
2. Write some code to fix the test you picked.
3. Re-run the tests to confirm the test is now passing.
4. Repeat from step 1.
5. Submit your solution (exercism submit /path/to/file)

Submissions are encouraged to be general, within reason. Having said that, it's also important not to over-engineer a solution.

It's important to remember that the goal is to make code as expressive and readable as we can. However, solutions to the hello-world exercise will not be reviewed by a person, but by rikki- the robot, who will offer an encouraging word.

Go through the setup instructions for JavaScript to install the necessary dependencies:

http://exercism.io/languages/javascript

Execute the tests with:

jasmine-node .

In many test suites all but the first test have been skipped.

Once you get a test passing, you can unskip the next one by changing xit to it.

This exercise has two files:

• hello-world.js
• hello-world.spec.js

The first file is where you will write your code. The second is where the tests are defined.

The tests will check whether your code is doing the right thing. You don't need to be able to write a test suite from scratch, but it helps to understand what a test looks like, and what it is doing.

Open up the test file, hello-world.spec.js. It has three tests defined in it.

This is the first test:

it('says hello world with no name', function() {
  expect(helloWorld.hello('')).toEqual('Hello, World!');
});

Run the test now, with the following command on the command-line:

jasmine-node .

The test fails, which makes sense since you've not written any code yet.

The failure looks like this:

1) Hello World says hello world with no name
   Message:
      Expected undefined to equal 'Hello, World!'.

There's more, but this is the most important part.

Take a look at that first line:

1) Hello World says hello world with no name

Now look at the test definition again:

it('says hello world with no name', function() {
  // ... more code here ...
});

The text 'says hello world with no name' is repeated. This is how you know which test failed.

The failure message explains what is wrong:

Expected undefined to equal 'Hello, World!'.

This comes from the part of the test definition that says "expect":

expect(helloWorld.hello('')).toEqual('Hello, World!');

It's comparing two values. It is calling

helloWorld.hello('')

and comparing the result to a hard-coded string.

'Hello, World!'.

So if you look at the failure message again, the hello function is returning undefined.

Try changing the function in hello-world.js so that it says

HelloWorld.prototype.hello = function(input) {
    return "chocolate";
};

Then run the tests again from the command-line:

jasmine-node .

Notice how it changes the failure message.

Then change the implementation in hello-world.js again, this time to make the test pass.

Once the test is passing, look at the second test in hello-world.spec.js. It looks like this:

xit('says hello to bob', function() {
  expect(helloWorld.hello('Bob')).toEqual('Hello, Bob!');
});

This test starts with xit instead of it. That means that when jasmine-node runs the tests, the test will be skipped.

Change the test so that it starts with it, and run the tests again.

Make the test pass, and then do the same with the third test.

When you are done, submit your solution to exercism:

exercism submit hello-world.js

This is an exercise to introduce users to using Exercism http://en.wikipedia.org/wiki/%22Hello,_world!%22_program

It's possible to submit an incomplete solution so you can see how others have completed the exercise.