Tag: javascript

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How to Add a Script to Minify your JavaScript in a package.json file

Recently I was working on a project where I wanted to set up a process that could combine and minify the JavaScript I had in a specific folder for a project. So how did I do it?

I decided to run the npm init command on my project folder. Within the package.json file, I had the following:

{
  "main": "scripts.js",
  "scripts": {
  "minify": "uglifyjs ./js/* -o scripts.min.js",
  "uglify": "npm run minify"
},
  "dependencies": {
  "uglify-js": "^2.8.8"
},
  "devDependencies": {
  "uglify-js": "^2.8.8"
 }
}

Once I ran npm install uglify-js --save, I made sure to specify the folder I wanted to run the process in (./js/*), and the file I wanted to create with the minified code (scripts.min.js). Next, all I had to do was run npm run uglify and my new scripts.min.js minified file was created.

Now whenever I make changes or add new files to my project’s JavaScript folder, I can run npm run uglify to bundle up and minify the code.

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A Brief Overview of ES6

ECMAScript 6, or ES6, is a newer version of JavaScript. It has several unique capabilities that weren’t possible in previous versions of JavaScript, for example:

  • Variables can be set with the terms let and const
  • The let keyword is used for block scoping so it doesn’t affect global values
  • The const keyword is used to protect the value of certain variables – you use this keyword for values that shouldn’t be reassigned
  • It allows you to use template strings to tap into the functionality of template languages to format your JavaScript code with variables like so: `${yourVariableHere}`
  • The spread operator can turn elements of an array into arguments of a function call or into elements of an array literal
  • Allows us to make classes in JavaScript (can create one super class that other classes inherit)
  • Can pass default values in functions for when you don’t explicitly pass anything for them

In order for browsers to understand ES6, you need to transpile the code. Babel, Traceur, and Closure are used for transpiling code, although Babel is known for supporting the most ES6 features.

For larger scale projects, you can use build tools like Webpack with ES6 – this allows us to load our dependencies. Npm creates a package.json file that runs dependencies.

 

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Yarn: the JavaScript Package Manager

If you already use npm, you’re probably wondering what’s the point of Yarn?

Yarn is a somewhat new JavaScript package manager created by the engineers at Facebook.

  • It’s a faster and more secure dependency manager
  • It uses an offline cache – so after you’ve installed a package using Yarn, it will be available on your machine for offline access.

Quite honestly, what really reeled me in with Yarn was the speed at which it can install packages. It’s amazing how shaving off a few seconds from installing packages can really speed up your overall workflow.

Get Yarn

npm install –g yarn

Or use brew to add it. Once installed, you use the following format to add any dependency:

yarn add <name of package>

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A Brief Overview of React.js

React is a user interface library that was developed at Facebook. React is written in different components and follows the principles of immutable data. It’s often used in enterprise applications, and it makes creating single page applications easier since they have a higher speed thanks to the virtual DOM. This means it writes to the browser DOM only when it is needed, instead of re-rendering an entire view when a change is made.

Virtual DOM

React creates an in-memory DOM where it only renders different parts of the DOM when a change occurs.

JSX

React utilizes JSX, which is a JavaScript extension syntax that allows you to quote HTML.

Babel

Babel is a transpiler that transpiles JavaScript code. It works for JSX as well as ES6 and beyond. Babel converts React’s JSX and ES6 to something the browser can use.

Components

React applications consist of a collection of components. Components are small user interface elements that display data as it changes over time. Used together, these components create entire user interfaces.

Component Lifecycle

Component lifecycles allow you to add libraries and load data at specific times. They also help improve the speed of an application, with lifecycle methods that you can override to run code a specific times in the process.

Mounting methods are called when an instance of a component is being created:

  • getInitialState()
  • componentWillMount()
  • componentDidMount()

Updating methods occur when a change happens to props or state:

  • componentWillReceiveProps()
  • shouldComponentUpdate()
  • componentWillUpdate()
  • render()
  • componentDidUpdate()

Unmounting methods are called when a component is being removed:

  • componentWillUnmount()

 

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A Brief Overview of Node.js and Express.js

If you’ve worked with JavaScript frameworks and libraries, chances are that you’ve heard of Node.js and Express.js. So for those who are unfamiliar to these terms – what exactly are they?

Node.js

Node.js is an open-source JavaScript runtime environment, that uses Google’s V8 JavaScript engine, where you can build server applications. Node.js is not a framework, although it has many modules that are written in JavaScript. It has event-driven architecture that is capable of asynchronous I/O, otherwise none as a form of input/output processing that allows other processing to continue before the transfer of data has finished.

Express.js

Express.js is a web application framework for Node.js, that’s used for building APIs. It is also known for being a backend component of the MEAN stack.

I’ve worked with Node.js and Express.js to create APIs, so I feel like I can never think about one of them without having the other one come to mind.