There are a number of built-in tasks that npm can run for you.

The most common is test.

You're often encouraged to install test frameworks and

build systems globally with the -g flag.

But that can be a little overkill if you're working on different projects with

potentially different versions.

Let's install our depth dependences now by running npm install.

The install command installs all npm modules that are part of your project.

In other words, third party modules that your project depends on.

But it also installs development dependencies,

that is, modules that you use during development.

Such modules that can compile Sass, combine multiple JavaScript files,

or to test your code to make sure it works.

In this example, I've installed the JavaScript testing framework Mocha for

testing my JavaScript.

How do you run Mocha here?

In your node_modules folder, there's a hidden directory, .bin.

And in there, there are command line executables like Mocha.

So you can type, node_modules/.bin/mocha.

And it runs.

However, you can run executables from npm without typing in this long command.

Let's update the test task in our scripts object with the Mocha command.

This will run any Mocha test in the project.

What we’ve done here is created a test task.

Now you can run it by typing npm run test.

Npm can run any binary or command line application.

See how much easier this is?

Now that we don’t need to remember or type that full path in to Mocha.

We can make it even easier by ditching run.

Because test is a built-in task, you can leave out the run,

and simply type npm test.