User:Roger Pearse/JavaScript Basics

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JavaScript Language

Installing stuff with NPM

Download and install nodejs. That gives you npm. This will end up in c:\program files.

Then you can install tools globally, or inside the project. Things like npm are global; things like Jasmine and Mocha are put inside the project.

Install into the project

Install tools into the project using: 

npm install karma --save-dev

Rather than globally with 

npm install karma -g

because then you aren’t dependent on local PC configuration. It's part of the project, in other words.

What’s –save-dev? That’s an option that inserts an entry pointing to the installed packages in the ‘devDependencies’ section of the package.json file. It signifies that a developer will need this package to work with the application, but it’s not required to run the application i.e. in production. So this is test-only stuff.

http://www.bradoncode.com/blog/2015/05/19/karma-angularjs-testing/

Starting a new node project

Start any node.js project by: 

mkdir MyProject
cd MyProject
echo {} >> package.json

Starting the project 2

Npm's init command line option will launch a wizard, which creates a package.json for our project. 

npm init

Do this after creating the directory.

Path problem in Windows

If you find that stuff installed with npm is not in the path in git bash, this means that when node was installed, the idiot didn't install as administrator, and the path stuff ended up in his local environment variables, rather than in the system environment variables. Might be able to fix via Windows | env, manually. Otherwise deinstall node from Control Panel, and reinstall.

Editor

Getting started with VS Code

Dark IDE seems to be a point of pride for JavaScript IDE's - you're not a professional unless you are using that.

Comparison of IDE's (googled for node js ide) - useful! https://www.slant.co/topics/46/~best-ides-for-node-js

Webstorm is in first place, but VS Code is next, and free.

But Webstorm includes code coverage in IDE, whereas VS Code has to use the paid for Wallaby.

Node.js

NodeJs is a way to run JavaScript to create server-side json-based webservices very lightly. The MEAN stack - NodeJs and Mongo - is intended to replace the LAMP stack with PHP and Postgres, and scales and runs far faster.

Noddy example

My first js (saved in myfirst.js): 

'use strict'

// Based on:
//   https://www.w3schools.com/nodejs/nodejs_get_started.asp
// Revised against:
//   https://nodejs.org/api/synopsis.html

// Get a handle on the http interfaces in node.js
// originally had "var" - use const (for immutable) or let (for assignable)
const http = require('http');

const hostname = '127.0.0.1';
const port = 8080;

// Create a server and pass a function in to listen to the request.
// The function passed in is a "request listener" which is automatically added to the "request" event
// The createServer() returns a new instance of http.Server
// In the horrible condensed way of js, the server is activated at the same time by .listen() on the end,
// in the original example.  But split out in the node.js docs, so have done the same
const myServer = http.createServer(function (request, response) {
     response.writeHead(200, {'Content-Type': 'text/html'});
     response.end('Hello World!');
});

myServer.listen(port, hostname); 

console.log("Not blocked by the listen");

File:NoddyJs.zip

Create a file, then in git bash (or in the VS code terminal) do 

node myfirst.js

Then open Chrome and do http://localhost:8080, and see the hello world.

Modules available for nodejs

The above example uses the http module. Here's a list of all of them in node 6: https://www.w3schools.com/nodejs/ref_modules.asp

Express

MVC framework built on Node. Has an express generator that will build the project dirs. From here:

Install the Express Generator by running the following from a terminal: 

npm install -g express-generator

The -g switch installs the Express Generator globally on your machine so you can run it from anywhere. You won't want it as part of your project anyway.

We can now scaffold a new Express application called myExpressApp by running: 

express myExpressApp

This creates a new folder called myExpressApp with the contents of your application. To install all of the application's dependencies (again shipped as NPM modules), go to the new folder and execute npm install: 

cd myExpressApp
npm install

At this point, we should test that our application runs. The generated Express application has a package.json file which includes a start script to run node ./bin/www. This will start the Node.js application running.

From a terminal in the Express application folder, run: 

npm start

The Node.js web server will start and you can browse to http://localhost:3000 to see the running application.

Colours in console

npm install chalk

and 

const chalk = require('chalk');

console.log(chalk.blue('Hello world!'));


Unit Testing

Mocha seems to have the lead...

Jasmine is used for BDD

My NoddyJasmine.htm, which you just open in Chrome, is: 

<html>
	<head>
		<link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.3.3/jasmine.min.css">
		<script src="https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.3.3/jasmine.min.js"></script>
		<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.3.3/jasmine-html.min.js"></script>
		<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jasmine/2.3.3/boot.min.js"></script>
	</head>
	<body>
	</body>
	<script type="text/javascript">

		// Paste in the test code here.
        // This example from
        // http://www.bradoncode.com/blog/2015/05/12/angularjs-testing-getting-started/

        // The describe function represents a spec (logical grouping of tests). 
        describe('calculator', function () {

            // The it function indicates a test within the logical grouping. 
            // The first bit is the displayed test name, the function is the actual test
	        it('1 + 1 should equal 2, others', function() {

	            expect(1 + 1).toBe(2);

                // Other possible tests using Jasmine's expect() method
                expect(true).toBe(true);
                expect(false).not.toBe(true);
                expect(1).toEqual(1);
                expect('foo').toEqual('foo');
                expect('foo').not.toEqual('bar');
            });

        });

	</script>
</html>

Mocking

Use Sinon instead of Mockito. There’s a before() and after() function. Stub the xhtmlrequest calls.

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