JavaScript Basics

Including JavaScript in an HTML Page

<script type="text/javascript"> //JS code goes here </script>

Call an External JavaScript File

<script src="myscript.js"></script>

Including Comments

// Comment

/* comment here */

Variables

var, const, let
var — The most common variable. Can be reassigned but only accessed within a function. Variables defined with var move to the top when code is executed.
const — Can not be reassigned and not accessible before they appear within the code.
let — Similar to const, however, let variable can be reassigned but not re-declared.

Data Types

var age = 23

var x

var a = "init"

var b = 1 + 2 + 3

var c = true

const PI = 3.14

var name = {firstName:"John", lastName:”Doe"}

Objects Example

var person = { firstName:"John", lastName:"Doe", age:20, nationality:"American" };