A module is a self-contained unit of code, which is usually stored in a file. In ES6, modules get language-level support for component definition. Modules export values, which can then be imported by other modules.

Sass control directives helps creating libraries for reuse and distribution, there by contribute to writing leaner Sass. Advanced frameworks use mixins. These mixins use directives such as @if, @for, each and @while.

If you are familiar with JavaScript, you have probably known the term scope. If you are familiar with other languages, you would know that a scope of a variable is to the nearest block – block scope. But JavaScript is different. A variable created with var will be scoped to the nearest parent function.

Gulp is a JavaScript task runner. It’s an alternative to Grunt, which allowed you to define your tasks using JavaScript inside of a file called Gruntfile.js. In this tutorial, I’ll show you how to install Gulp and create a simple configuration file to get your feet wet with this great new task runner.

The destructuring assignment syntax is a JavaScript expression in ES6 that makes it possible to extract data from arrays or objects using a syntax that mirrors the construction of array and object literals.

Webpack is a module bundler. Webpack takes modules with dependencies and generates static assets representing those modules.

Arrow functionss are a function shorthand using the => syntax (fat arrow). They are syntactically similar to the related feature in C#, Java 8 and CoffeeScript. They support both expression and statement bodies. Unlike functions, arrows share the same lexical this as their surrounding code.

Grunt is a task runner that has a ton of plugins for doing things like compiling LESS/SASS into CSS, concatenating JavaScript, minifying, etc. It also has a package for watching files (the same way CodeKit and Prepros does) and firing off certain tasks when they’re modified.

A closure is an inner function that has access to the outer (enclosing) function’s variables—scope chain.