javascript.md

JavaScript Cheat Sheet

Regular Expressions Syntax

Expression	Description
^	Start of string
$	End of string
.	Any single character
**`(a	b)`**
(...)	Group section
[abc]	In range (a, b or c)
[^abc]	Not in range
\s	White space
a?	Zero or one of a
a*	Zero or more of a
a*?	Zero or more, ungreedy
a+	One or more of a
a+?	One or more, ungreedy
a{3}	Exactly 3 of a
a{3,}	3 or more of a
a{,6}	Up to 6 of a
a{3,6}	3 to 6 of a
a{3,6}?	3 to 6 of a, ungreedy
\\	Escape character
[:punct:]	Any punctuation symbol
[:space:]	Any space character
[:blank:]	Space or tab

Pattern Modifiers

Modifier	Description
g	Global match
i	Case-insensitive
m	Multiple lines
s	Treat string as a single line
x	Allow comments and whitespace in pattern
e	Evaluate replacement
U	Ungreedy pattern

JavaScript RegExp Object Methods

Method	Description
compile()	Recompiles the regular expression
exec()	Executes a match and returns results
test()	Tests if pattern exists in string
lastIndex	Returns the last index matched
lastMatch	Returns the last match found
lastParen	Returns the last captured group

JavaScript Event Handlers

Event Handler	Description
onabort	Triggered when an operation is aborted
onmousedown	Mouse button pressed down
onblur	When an element loses focus
onmouseover	When mouse pointer hovers over an element
onclick	When an element is clicked
onkeydown	When a key is pressed down
onkeyup	When a key is released
onload	When the page or image is loaded

JavaScript Arrays

Method	Description
concat()	Combines two or more arrays
slice()	Returns a shallow copy of a portion of an array
join()	Joins elements of an array into a string
sort()	Sorts the elements of an array
push()	Adds an element to the end of an array
pop()	Removes the last element from an array

JavaScript Numbers and Maths

Method	Description
abs()	Returns the absolute value
max()	Returns the largest number
min()	Returns the smallest number
pow()	Returns base raised to the power of exponent
sqrt()	Returns the square root
random()	Returns a random number between 0 and 1

JavaScript Booleans

Method	Description
toSource()	Returns a string representing the Boolean object
valueOf()	Returns the primitive value of a Boolean

JavaScript Dates

Method	Description
Date()	Returns the current date and time
getDate()	Gets the day of the month
getDay()	Gets the day of the week
setFullYear()	Sets the year for a date object
setTime()	Sets the date and time in milliseconds

JavaScript Strings

Method	Description
charAt()	Returns the character at a specified position
indexOf()	Returns the position of the first occurrence of a substring
toLowerCase()	Converts a string to lowercase
toUpperCase()	Converts a string to uppercase
replace()	Replaces occurrences of a substring with another

JavaScript Functions

Method	Description
decodeURI()	Decodes a URI string
isNaN()	Checks if a value is NaN
encodeURI()	Encodes a URI string
parseInt()	Converts a string to an integer
eval()	Executes a string of code