JavaScript (JS) Refresher for React

A quick refresher on the JS concepts needed to learn and understand React

Photo by Pankaj Patel on Unsplash

General

• Scripting language — interpreted at runtime instead of compile time
• Interpreted — it is interpreted at runtime by the client browser instead of being passed through a compiler that converts the code to byte code
• Supports OOP (object-oriented programming)
• Object libraries — Document Object Model (DOM)
• React uses the ES6 (EcmaScript / published in 2015) version of JS

Incorporating JS in HTML

You can incorporate JS in HTML using the <script> tag:

Input/Output

Write

To an element on a page:

• The item must already exist on the page
• document.getElementById("result").innerHTML = "hello";

To a page:

• document.write(“Hello”);
• document.writeln(“Hello”);