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Overview
4:21In this video we'll take a brief overview to on task running with npm.
[SOUND] Hello there, I'm Andrew, and
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welcome to this workshop on
using npm as a task runner.
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A task is something that you need to do.
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If you want to perform that task over and
over again,
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you'll save yourself a lot of time
if you alternate the process.
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Common web development tests
include running test suites.
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Compiling SaaS, TypeScript and
CoffeeScript files.
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Downloading assets of files from an
external source that your package needs.
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Starting a web server.
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And starting a worker that
goes through a queue of jobs,
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like sending out emails or
push notifications.
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Popular jump script build tools like grunt
and group are good for complex projects.
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But you don't always need that power or
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want to bother with the time consuming
set up process that they require.
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You can always turn to
a full feature build system
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later as your project evolves.
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npm tests are called scripts, and
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they're added to the scripts property
of a project's package.json file.
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Tasks have a name and a command,
which is simply a string that's
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executed on the operating system's
command line when the task is run.
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For example, you could echo out a message
to the terminal, start up a web server,
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or use a command line like mv to
move files, or cp to copy files.
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I'll show you a few examples in a moment.
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Once you have the script added to the
package.json file, you can run it simply
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by typing npm run, the name of the script
in your computer's command line tool.
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For example, if you had a task named test,
you'd run it by typing npm run test.
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Or if I had a script named compile,
that compiles CSS files,
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I'd run it with npm run compile.
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I'll focus on two types of task with MPM.
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Default, or built-in tasks,
and arbitrary tasks.
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Built-in tasks are those that
are common to most projects.
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An example of a built-in task is "test".
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Built-in tasks do not
require the run command.
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So npm run test can also
be ran as npm test.
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That saves a couple of keystrokes
every time you want to run your tests.
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Arbitrary tasks are those
that you can name yourself.
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They require npm’s run command.
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Since there's no built-in compile task,
if you added your own
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script with that name,
you'd read it like this, npm run compile.
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Not all JavaScript applications will need
custom or arbitrary tasks like this,
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since the built-in task cover many
of the most common situations.
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Here's the simple project
we're building in this video.
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Dice Simulator 2015 is the latest craze.
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You click the button and
it rolls the dice.
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This project is a front end project.
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When I say we'll be building this, I don't
mean that we'll be programming this.
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All the programming has been done, but
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we'll be getting the project
ready to deploy.
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Open up the associated work space
with this video and we'll get going.
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Let's take a look at the start
point of this project.
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We have a srcc folder or source folder.
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A test folder, with a simple test for
this application.
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And we can use npm's built
in test task for this.
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Let's jump in quickly to the package.json
file and see what's going on in there.
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We'll be using Mocha as
our test library and
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UglifyJs to combine our JavaScript
files into one app.js file.
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The scripts object has a test task.
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If you don't specify your test, it prints
out, Error: no test specified, and
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it exits with a 1,
meaning something went wrong.
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Computer programs successfully
run exits with the code of 0.
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The thing that's wrong here,
is that we have no test set up.
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We'll do that in the next video.
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