JS built-in objects

Standard built-in objects

• Constructor Object

Object Boolean String number Function Array RegExp Date Error

• Other objects

Math Json Global Object

1. Object

Methods for instantiating objects

var obj = {' name ': Mary, age:24};

　The object constructor has no instance object properties and methods

Object.creat

--Create a new object based on a prototype object

var proto = {a:1, B:2};var obj = Object.creat (proto);

Object.prototype.toString

--GET method caller standard type

var obj = new Object (); obj.tostring ();  "[Object Object]"

Object.prototype.hasOwnProperty

--Determine whether a property is an object's own property

var obj = {a:1, b:2};
OBJ.C = 3;
Obj.hasownproperty ("C"); True
Obj.hasownproperty ("a"); False

2. String, number, BooleanBoolean

Converting other types to Boolean values

Numbers: 0, Nan->false

String: ""->false

Undefined->false

Null->false

Object->true

String

Use of strings

String.prototype.indexOf

--Gets the index position of the substring in the string ( returns 1 if it does not exist )

String.prototype.replace

Find string replaced with target character

A regular expression is used here.

String.prototype.split

--Split the string into a string array by the delimiter

NumberNumber.prototype.toFixed

--Rounds num to a number that specifies the number of decimal digits

3. Array

Creation of arrays

var true function (){}];
var arr = new Array (1, "a", true, function () {});

• Constructor object Properties, method

--prototype, IsArray

• Prototype object properties, methods

--constructor, splice, ForEach, Find, concat, pop, push, reverse, shift, slice ...

• Instance object properties, methods

--Length

Array.prototype.splice

--Add or remove elements from an array, returning the list of deleted elements

Array.prototype.splice

--Iterate over the array elements and invoke the callback function

The resulting result is: 2 True 5 true 9 true

Skipped an empty element.

4. Function

Instantiating a function method

Function.prototype.apply

--To specify the caller of the function and the function parameters by parameter, and then execute the function

functionPoint (x, y) { This. x =x;  This. y =y;} Point.prototype.move=function(x, y) { This. x + =x;  This. Y + =y;}varp =NewPoint (0, 0);p. Move (2, 2);//move to point 2varCircle = {x:1, y:1, r:1};p. move.apply (Circle, [2, 1]);//{x:3, y:2, r:1}

Function.prototype.bind

--Same as specifying function callers and function arguments, but returning this function should refer to the

Make the following changes based on the above code:

var circlemove = P.move.bind (Circle, 2, 1// Set Timer to move the circle after 1s

Custom Object Builder

Sub-class constructors

Function call mode

• ()
• Apply, call

function parameters

• The number of formal participation arguments is not necessarily equal
• Value passing
• To check implementation function overloading by parameter type

Argument

Compares an indefinite number of numeric sizes and returns a large number:

function Max () {       var _max = arguments[0];         for (I =0; i < arguments.length; i++) {            if(_max < arguments[i] {                 =  Arguments[i];             }       }        return _max;}

Value passing

function Plus (num) {       return + +num;} var count = ten; var ret = plus (count);

Results: ret = = = 11; Count = = 10;

function SetName (obj) {       = "Obama";} var president = {name: "Bush"};setname (president);

At this point, obj and President point to the same heap object, and obj replicates only the address in the Stack object, so the result is: {name: "Obama"}.

function overloading

5. RegExp, Date, ErrorRegExp

Defining methods

--/pattern/flags

--New REGEXP (pattern[, flags]);

Test () method

--use regular expressions to test strings and return test results

var reg =/^abc/i;  // start with ABC, ignoring the case reg.test ("Abc123");  // truereg.test ("Ferabc");  // false

Date

Defining methods

var New Date (); var New Date (2018, 3, 10, 7, 1, 1, 100);

6. Math, JSONMath

Object methods

 //  floor: Rounding down  math.floor (0.97); //  0   Math.floor (-5.1); // -6  //  ceil: Rounding up   Math.ceil (1.2); //  2  //  round: rounding    Math.Round (3.4); //  3  //  random: Takes a stochastic number and returns the floating-point numbers between 0~1   Math.random (); // 0.4534623634643   Math.random (); // 0.2048253468450  

JSON

--for storing and exchanging textual information

Json.stringify

--Serializing a JSON object into a string

var json = {1:1, 2: ' 2 ', 3:{4:4, 5:{6:6}}; Json.stringify (JSON);    //

Json.parse

--Converts a JSON string into a JSON object

7. Global Objects

• . Non-numeric value NaN

--Indicates the result of an error or meaningless operation

--Nan participates in the Operation return is still Nan

-Nan is not equal to any value, including its own

--You can use isNaN () to determine whether the result of the operation is Nan

• parseint

--Convert a string to a number

• Encodeduricomponent

--Used to encode Chinese, special characters, etc. in the URI parameter as part of the URI

var url = "http://www.163.com/reg.html?name=" + encodeduricomponent (name);

JS built-in objects