Reference

Global

decodeURI()

Decodes a string escaped with encodeURI().

decodeURIComponent()

Decodes a string escaped with encodeURIComponent().

encodeURI

Encodes a URI by escaping certain characters.

encodeURIComponent

Encodes a URI component by escaping certain characters.

escape()

Encodes a string by replacing certain characters with escape sequences.

eval()

Evaluates a string of JavaScript code and returns the result.

isFinite()

Tests whether a value is a finite number.

isNaN()

Tests whether a value is the not-a-number value.

parseFloat()

Parses a number from a string.

parseInt()

Parses an integer from a string.

unescape()

Decodes a string encoded with escape().

Array

Array.concat()

Returns A new array

    var a = [1,2,3];
    a.concat(4, 5) // Returns [1,2,3,4,5]

Array.every()

test whether a predicate is true for every element

    [1,2,3].every(function(x) { return x < 5; }) // => true: all elts are < 5

Array.filter()

return array elements that pass a predicate

    [1,2,3].filter(function(x) { return x > 1; }); // => [2,3]

Array.forEach()

invoke a function for each array element

This method returns nothing.

    var a = [1,2,3];
    a.forEach(function(x,i,a) { a[i]++; }); // a is now [2,3,4]

Array.indexOf()

    ['a','b','c'].indexOf('b') // => 1

Array.lastIndexOf()

search backward through an array

Array.join()

concatenate array elements to form a string

    a = new Array(1, 2, 3, "testing");
    s = a.join("+"); // s is the string "1+2+3+testing"

Array.map()

compute new array elements from old

    [1,2,3].map(function(x) { return x*x; }); // => [1,4,9]

Array.push()

append elements to an array

Array.pop()

remove and return the last element of an array

The new length of the array, after the specified values are appended to it.

    var stack = []; // stack: []
    stack.push(1, 2);  //stack: [1,2]  Returns 2
    stack.pop(); // stack: [1] Returns 2

Array.reduce()

compute a value from the elements of an array

    [1,2,3,4].reduce(function(x,y) { return x*y; }) // => 24: ((1*2)*3)*4

Array.reduceRight()

reduce an array from right-to-left

    [2, 10, 60].reduceRight(function(x,y) { return x/y }) // => 3: (60/10)/2

Array.reverse()

reverse the elements of an array

    a = new Array(1, 2, 3); // a[0] == 1, a[2] == 3;
    a.reverse(); // Now a[0] == 3, a[2] == 1;

Array.shift()

shift array elements down,The former first element of the array.

    var a = [1, [2,3], 4]
    a.shift(); // Returns 1; a = [[2,3], 4]

Array.slice()

return a portion of an array

    var a = [1,2,3,4,5];
    a.slice(0,3);
    a.slice(3);
    a.slice(1,-1);

Array.some()

test whether a predicate is true for any element This method is very much like every()

Array.splice()

insert, remove, or replace array elements

    var a = [1,2,3,4,5,6,7,8]
    a.splice(1,2); // Returns [2,3]; a is [1,4]
    a.splice(1,1); // Returns [4]; a is [1]
    a.splice(1,0,2,3); // Returns []; a is [1 2 3]

Array.toLocaleString()

convert an array to a localized string

Array.toString()

This return value is the same string that would be returned by the join() method with no arguments. convert an array to a string

Array.unshift() insert elements at the beginning of an array

    var a = []; 
    a.unshift(1); // a:[1]
    a.unshift(22);// a:[22,1]

String

String.charAt()

get the ‘n’th character from a string

String.indexOf()

search a string

String.lastIndexOf()

search a string backward

String.match()

find one or more regular-expression matches

    "1 plus 2 equals 3".match(/\d+/g) // Returns ["1", "2", "3"]

String.replace()

replace substring(s) matching a regular expression

String.search()

search for a regular expression

String.slice()

string.slice(start, end)

extract a substring

    var s = "abcdefg";
    s.slice(0,4)// Returns "abcd"

String.split()

break a string into an array of strings

String.substr()

string.substr(start, length)

extract a substring

String.substring()

string.substring(from, to)

return a substring of a string

String.toLowerCase()

convert a string to lowercase

String.toUpperCase()

convert a string to uppercase

Date

Function

.call

.apply

.bind

JSON

JSON.parse()

parse a JSON-formatted string

JSON.stringify()

serialize an object, array or primitive value

Math

Math.abs()

Computes an absolute value.

Math.ceil()

Rounds a number up.

Math.exp() Computes a power of e.

Math.floor() Rounds a number down.

Math.log() Computes a natural logarithm.

Math.max() Returns the larger of two numbers.

Math.min() Returns the smaller of two numbers.

Math.pow()

Computes x y

Math.random()

Computes a random number.

Math.round() Rounds to the nearest integer.

Number

Number.toExponential()

format a number using exponential notation

    var n = 12345.6789;
    n.toExponential(1);// Returns 1.2e+4
    n.toExponential(5); // Returns 1.23457e+4
    n.toExponential(10);
    n.toExponential();

Number.toFixed()

format a number using fixed-point notation

    var n = 12345.6789; 
    n.toFixed(); // Returns 12346: note rounding, no fractional part
    n.toFixed(1); // Returns 12345.7: note rounding
    n.toFixed(6); 
    (1.23e+20).toFixed(2);
    (1.23e-10).toFixed(2) // Returns 0.00

Number.toPrecision()

format the significant digits of a number

    var n = 12345.6789;
    n.toPrecision(1); // Returns 1e+4
    n.toPrecision(3); // Returns 1.23e+4
    n.toPrecision(5);
    n.toPrecision(10);

Object

Object.hasOwnProperty()

check whether a property is inherited

    var o = new Object();
    o.x = 3.14; 
    o.hasOwnProperty("x"); // Returns true: x is a local property of o