JavaScript自学(4)
1、JSON对象
2、面向对象原型继承
<script>
// var user={
// "name":"*",
// "age":3,
// "sex":"男"
// };
// //对象转化为json字符串 {"name":"*","age":3,"sex":"男"}
// var jsonUser=JSON.stringify(user);
//json字符串转化为对象 参数为json字符串
// var obj=JSON.parse('{"name":"*","age":3,"sex":"男"}')
var Student={
name:"cj",
age:3,
run:function (){
console.log(this.name+"run...");
}
};
var xiaoming={
name:"小明"
};
//小明的原型是Student
//原型对象。
xiaoming.__proto__=Student;
var Bird={
fly:function (){
console.log(this.name+"fly...");
}
}
xiaoming.__proto__=Bird;
</script>
3、面向对象class继承
本质:查看对象原型
原型链
proto:
<script>
//ES6之后
//定义一个学生类
class Student{
constructor(name) {
this.name=name;
}
hello(){
alert("Hello");
}
}
class pupil extends Student{
constructor(name,grade) {
super(name);
this.grade=grade;
}
myGrade(){
alert("我是一名小学生!");
}
}
var xiaoming=new Student("xiaoming");
var caiwei=new pupil("*",1)
</script>
4、操作BOM对象
5、获得DOM节点
<div id="father">
<h1>标题一</h1>
<p id="p1">p1</p>
<p class="p2">p2</p>
</div>
<script>
//对应css选择器
let h1 = document.getElementsByTagName("h1");
let p1 = document.getElementById("p1");
let p2 = document.getElementsByClassName("p2");
let father = document.getElementById("father");
let childrens = father.children;
// father.firstChild;
// father.lastChild;
</script>