原型函数

今天偶然看到一个原型的博客，看了之后还是不懂，然后就自己看书，然后看了原型函数

恩，上代码呗

<!DOCTYPE html>
<html>
<head>
    <meta charset='UTF-8'>
    <title>prototype</title>
</head>
<body>

</body>
<script type="text/javascript">
    function person(){

    }
    person.prototype.name='wenwen';
    person.prototype.age=23;
    person.prototype.job='engi';
    person.sayName=function(){
        alert(this.name);
    }
    var person1=new person;
    var person2=new person;
    console.log(person1.name);//wenwen
    console.log(person2.name);//wenwen
    
</script>
</html>

这就是原型函数呢

这个也可以实例修改值

var person1=new person;
	var person2=new person;

	person1.name='hello';
	console.log(person1.name);//hello
	console.log(person2.name);//wenwen

就是这样

然后还有个判断属性是实例属性还是原型属性的，就是hasOwnProperty()方法

        var person1=new person;
    var person2=new person;

    person1.name='hello';
    console.log(person1.name);//hello
    console.log(person2.name);//wenwen
    console.log(person1.hasOwnProperty('name'));//true
    console.log(person2.hasOwnProperty('name'));//false

而且就是delete可以删除实例属性，但是不能删除原型属性，不信看代码

    var person1=new person;
    var person2=new person;

    delete person1.name;
    console.log(person1.name);//wenwen
    console.log(person2.name);//wenwen

var person1=new person;
    var person2=new person;
    person1.name='hello';
    delete person1.name;
    console.log(person1.name);//wenwen
    console.log(person2.name);//wenwen

还有个in操作符咯，in操作符会通过对象能够访问给定属性时返回true,无论该属性是在实例中还是原型中，

    var person1=new person;
    var person2=new person;
    person1.name='hello';
    delete person1.name;
    console.log(person1.name);//wenwen
    console.log(person2.name);//wenwen
    console.log('name' in person1);//true

还有更简单的原型语法

    person.prototype={
        name:'wenwen',
        age:23,
        job:'eng',
        sayName:function(){
            alert(this.name);
        }
    };