JavaScript object properties check add delete and access action instances

Check the properties

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

Increase the attributes

Define an object, dog, give it attributes, then color, and then iterate over all the attributes and values

var dog={
 name:" Mango. ",
 type:" The king of the would ",
 eat:function(){
  alert(" eat ");
 }
}
 Object.prototype.color=" white ";
 var name;
 for(name in dog){
  document.write(name+" "+dog[name]+"<br>")
 }

Results the following

name  Mango. 
type  The king of the would 
eat function (){ alert(" eat "); }
color  white 

Delete the properties

var cat = {
  "name": "tom",
  "sex": "man",
  "color": "yellow"
}
delete cat.name;
cat.sex = undefined;
cat.color = null;
alert("name Whether the attribute exists: " + cat.hasOwnProperty("name")); //false
alert("sex Whether the attribute exists: " + cat.hasOwnProperty("sex")); //true
alert("color Whether the attribute exists: " + cat.hasOwnProperty("color")); //true

To access attributes

var cat = {
  "name": "tom",
  "sex": "man",
  "color": "yellow"
}
var name1 = cat.name; // Object properties are accessed through the dot operator 
var name2 = cat["name"]; // Object properties are accessed through the brackets operator 

There are also two ways to create objects

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

var obj = {
  name : "MangGuo", //name It's the property name, "MangGuo" Is the value 
  age : 25
}