JavaScript object attribute inspection, addition, deletion, access operation examples_javascript skills

Check properties

var mouse = {
 "name": "betta",
 "age": 3,
 "varieties": "milaoshu"
}
 
mouse.hasOwnProperty("name"); // true
mouse.hasOwnProperty("sex"); //false

Add attributes

Define an object dog, then assign various attributes, then assign the color attribute, and finally traverse all attributes and values

var dog={
 name:"芒果",
 type:"会之王",
 eat:function(){
  alert("吃");
 }
}
 Object.prototype.color="白色";
 var name;
 for(name in dog){
  document.write(name+" "+dog[name]+"<br>")
 }

The effect is as follows

name 芒果
type 会之王
eat function (){ alert("吃"); }
color 白色

Delete attribute

var cat = {
  "name": "tom",
  "sex": "man",
  "color": "yellow"
}
delete cat.name;
cat.sex = undefined;
cat.color = null;
alert("name属性是否存在：" + cat.hasOwnProperty("name")); //false
alert("sex属性是否存在：" + cat.hasOwnProperty("sex")); //true
alert("color属性是否存在：" + cat.hasOwnProperty("color")); //true

Access properties

var cat = {
  "name": "tom",
  "sex": "man",
  "color": "yellow"
}
var name1 = cat.name; //通过点操作符来访问对象属性
var name2 = cat["name"]; //通过中括号操作符来访问对象属性

There are two ways to create objects

var obj = new Object();
obj.name = "MangGuo";
obj.age = 25;

var obj = {
  name : "MangGuo", //name是属性名，"MangGuo"是值
  age : 25
}