JS Reference type---Object

First, the basic knowledge of the object

• Concept: A particular thing, having characteristics (attributes) and behaviors (methods) that can store data.

• Popular understanding: An object is a set of unordered key-value pairs that can store data.

• Object's properties and methods: Can be . added in a way (this proves that JS is a dynamic type of language)

• The value of most reference types in JS, all Object instances of type

Two, the object creation 3 ways 1.{}creating objects by literal volume

<script>    var={};    obj2.name=‘zhangxin‘;    console.log(obj2);</script>

2.newConstructors Create objects

• Constructor: First letter uppercase (Convention); Normal function: First letter lowercase

<script>    var=newObject();    obj1.name=‘zhangxin‘;    console.log(obj1);</script>

• newConstructor, new do 4 things:

  • Create a new object

  • thispoint to the new object that is currently created

  • Add to New Object属性、方法

  • Return创建后的新对象

<Script>    function Computer(Name,Age{         This.name =Name;         This. Age =Age;         This.say = function(){            return ' I am ' +  This.name + '; this year ' +  This. Age;        }    }    varCp= New Computer(' computer ',  -);    Console.Log(CP.say());  //I am a computer; this year</script>

• new 构造函数Creating an Array Object

<script>    var arr = new Array();    console.log(arr);  // [] </script>

3.Object.create({键值对})method to create a new object; ES5 method, IE8 and the following incompatible

<script>    var o1 = {name: ‘zhangxin‘};    var create = Object.create(o1);    console.log(create.name);  // ‘zhangxin‘</script>

Third, the object's properties, methods (Assignment, take value) mode 1:.The way to add/read: Properties, method Mode 2:[]The way to add/read: Properties, methods(important)

• Important: You can add dynamic property names, dynamic method names

• Use [] the Add property, method: If the property name is fixed, quotation marks are required, otherwise it is considered a dynamic variable

<script>    var obj = {};        obj.age = 20;    obj[‘name‘] = ‘zhangxin‘;        console.log(obj.age);       // 20    console.log(obj[‘name‘]);   // ‘zhangxin‘</script>

Four, the object loop traversalfor-in

<script>    var={age:18,name:‘ss‘};        for (varin{        consloe.log(key);        console.log(obj[key]);    }</script>

V. Deep copy of ObjectObject.create( )

<script>    var={name:‘zhangxin‘};    var=Object.create(o1);    console.log=== o1);  // false</script>

JS Reference type---Object