JavaScript Cheat Sheet.pdf

JavaScript Cheat Sheet

JavaScript is a a loosely typed and dynamic scripting language developed for the Internet,

and a core technology of the the World Wide Web.

Variables

Variable names can contain uppercase or lowercase letters (Aa to Zz), or numbers (0 to 9),

or an underscore (_). They cannot start with a number.

Data type Global scope Block scope

number

var foo = 10; let foo = 10;

string

var foo = "example"; let foo = "example";

Boolean

var foo = true;

var foo = false;

let foo = true;

Binary operators Assignment shortcuts

a & b Bitwise AND (1 if both bits are 1) a += b;

Addition

a = a + b;

a | b Bitwise OR (1 if either bits are 1) a -= b;

Subtraction

a = a - b;

a ^ b Bitwise XOR (1 if bits differ) a *= b;

Multiplication

a = a * b;

a<<n Shift bits to the left a /= b;

Division

a = a / b;

a>>n Shift bits to the right a %= b;

Modulo

a = a % b;

Interacting with HTML

Set contents of any HTML element with ID

demo to the contents of variable foo

document.getElementById("demo").i

nnerHTML = foo;

Set contents of button element to the result

of the Date() function

<button onclick="this.innerHTML =

Date()">Timestamp</button>

Common HTML events

click drag / dragover / dragend drop

focus keydown / keypress / keyup input

load mousedown / mouseover / mouseup submit

Seth Kenlon CC BY-SA 4.0 Opensource.com