In JavaScript, it's important to understand and properly use these keywords to write effective and functional code. Misusing them or misunderstanding their functionalities can lead to errors or unexpected behavior in your programs.

Beginner’s Essential

Javascript Cheat Sheet




The language of the web.

,Table of Contents

Javascript Basics 2

Variables 2

Arrays 3

Operators 4

Functions 5

Loops 7

If - Else Statements 7

Strings 7

Regular Expressions 9

Numbers and Math 10

Dealing with Dates 12

DOM Node 14

Working with the Browser 18

Events 21

Errors 27




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, 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><code></code>


Including Comments
//
Single line comments

/* comment here */
Multi-line comments


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
Cannot 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
Numbers

var x
Variables



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