JavaScript – Cheat Sheet
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JavaScript
Cheat Sheet
OUTPUT
# This is a comment
/* This is a multi-line comment */
window.alert(“Hello World”)
Displays “Hello World” in an alert box
console.log(“Hello World”)
Writes “Hello World” into the browser console
DOM METHODS
These methods affect the overall HTML page.
document.getElementById(“id”)
Returns the element where id = “id”
document.getElementsByClassName(“class
”)
Returns a list of elements where class=”class”
document.createElement(“button”)
Creates a button element
element.childNodes
Returns all children elements within ‘element’
element.parentNode
Returns the predecessor of ‘element’
element.appendChild
Adds a DOM element to ‘element’
element.removeChild(child_element)
Removes ‘child_element’ from ‘element’
element.id
Returns or assigns an id to an element
element.class
Returns or assigns a class to an element
elementName.innerText = “Hello World”
Assigns text to an HTML element
EVENTS
Events occur only in certain circumstances; they’re
generally associated with functions.
document.onload
Occurs when the web page is initially loaded
element.onclick
Occurs when the element is clicked
element.onkeyup
Occurs when any key is pressed in the element
VARIABLES
Variables must be declared before they are used.
var number = 1;
var workshop = “Advanced Web Dev”;
var even_numbers = [2, 4, 6, 8];
ARITHMETIC OPERATORS
+ Add - Subtract * Multiply / Divide
++ Increase by one -- Decrease by one
STRING FUNCTIONS
var string = “javascript”;
string.length
Returns 10 – the length of the string
