0513JS数组的定义遍历添加

Posted 2020-11-04

|数组
|-定义方式
|--1、new Array();
|----空数组
|------var attr = new Array();
|------lenght:0
|------_proto_: Array []
|----有长度的数组
|------var attr new Array(10);
|------lenght:10
|------_proto_: Array []
|----带有初始值的数组
|------var attr = new Array("张三"，20，"男");
|------Array(3) [ "张三", 20, "男" ]
|------0: "张三"
|------1: "20"
|------2: "男"
|------lenght: 3
|------_proto_: Array []
|--2、[];
|----空数组
|------var attr = [];
|------lenght:0
|------_proto_: Array []
|----带有初始值的数组
|------var attr = ["张三", 20, "男"];
|------0: "张三"
|------1: "20"
|------2: "男"
|------lenght: 3
|------_proto_: Array []

var attr = new Array();
var attr = new Array(5);
var attr = new Array("张三",20,"男");
var attr = [];
var attr = [5];
var attr = ["张三",20,"男"];
console.log(attr);

|-数组的遍历
|--1、for循环
|--2、for(in)

var person = ["李四",28,"男","未婚"];
for(var i = 0;i < person.length;i++ ){
    alert(person[i]);
}
var person = ["李四",28,"男","未婚"];
for(var i in person){
    alert(person[i]);
}

|-数组的添加
|--1、for循环
|--2、.push

var attr = [];
for(var i = 0;i < 5;i++){
    attr[i] = i;
    attr.push(i);
}
alert(attr);