JavaScript quick reference

JavaScript quick reference

Statements

break terminates the current while or for loop

continue continues execution of the loop with the next iteration

for ([initial-expression;] [condition;] [increment-expression]) {
statements
} creates a loop

for (variable in object) {
statements
} creates a loop

if (condition) {
statements
} [else {
statements
}] executes a set of statements if a specified condition is true or false

switch(variable) {
 case value_1:
  statements;
  break;
...
  default:
  statements;
} can be used for multiple statements branches

while (condition) {
 statements
} creates a loop that executes a statements if condition is true

do {
 statements
} while (condition) creates a loop that executes a statements if condition is true

Math Functions

isNaN(value) is value not a number

parseFloat(string) returns a floating-point number

parseInt(string [,base]) returns an integer of the specified base

abs(value) absolute value of a number

sin(value), cos(value), tan(value), asin(value), acos(value), atan(value) trigonometric functions

max(x,y), min(x,y) highest/lowest value of x and y

String and Array Functions

length number of characters in a string or elements in array

charAt(index) character at a specified position

charCodeAt(index) character code at a specified position

concat(string1,string2...,stringN)
concat(array1,array2...,arrayN) Joins two or more strings or arrays and returns the result

eval(string) evaluates a string of JavaScript code

join(separator) joins elements of an array into a string and separate each element with separator

indexOf(searchvalue,fromindex) position of the first occurrence of a specified string value

lastIndexOf(searchvalue,fromindex) position of the last occurrence of a specified string value

replace(findstring,newstring) replaces findstring characters with newstring characters in a string

slice(start,end) extracts a part of a string or array and returns the extracted part

split(separator, array_size) splits a string by separator into an array of strings

substr(start,length)
substring(start,stop) returns the characters in a string between two specified indices

toLowerCase()
toUpperCase() returns a string in lowercase/uppercase letters

pop() removes and returns the last element of an array

push() adds element(s) to the end of an array

reverse() reverses elements position of an array

sort(sortby) sorts elements of an array

Date Functions

Date() today's date and time

getDate(), getMonth(), getFullYear(), getHours(), getMinutes(), getSeconds(), getMilliseconds()returns the selected value from a Date object

getDay() returns day of the month from a Date object

setMonth(month[,day]), setFullYear(year[,month,day]), setHours(hour[,min,sec,millisec]), setMinutes(min[,sec,millisec]) sets a date or time in a Date object

Events

onabort, onerror loading is interrupted / an error occurs when loading

onblur, onfocus element loses or gets focus

onchange field changed

onclick, ondblclick mouse clicks/doubleclicks on an object

onkeydown, onkeyup, onkeypress keyboard key pressed / released / pressed or held

onreset, onsubmit reset/submit form button is clicked

onload, onunload page is loaded/user close the page

onmousedown, onmousemove, onmouseout, onmouseover, onmouseup mouse movement events

onresize window is resized