js jq 字符串數組對象

數組是有序的，對象是無序，數組是特殊的對象

數組

聲明數組
var arr=new Array('red','blue','yellow');  //["red", "blue", "yellow"]
var arr=["red", "blue", "yellow"];
var arr=new Array();
     arr[0]='red';
     arr[1]='blue';
     arr[2]='yellow';

追加一個元素
arr.push('green');   //["red", "blue", "yellow","green"]

獲取數組的元素個數
var len=arr.length;

length的長度是根據索引得來

arr['name']='xiaozhu';
arr.length   //4

arr[8]='xiaozhu';
arr.length   //9

對象

聲明對象
var person = new Object();
    person.name = "xiaozhu";
    person.age = 21;
   
    var person = {
        name: "xiaozhu",
        age : 21
    }

//{name: "xiaozhu", age: 21}

 

字符串 數組 數組格式化（對象）

字符串轉數組
var str="a,s,d";
var arr = str.split(',');         // ["a","s","d"]  數組

數組轉數組格式化（字符串）
str = JSON.stringify(arr);        // ["a","s","d"]  字符串

數組格式化（字符串）轉數組
arr = JSON.parse(str );          // ["a","s","d"]  數組

 

JSON字符串轉換為JSON對象
var str = '{ "name": "cxh", "sex": "man" }';

var obj = eval('(' + str + ')');    //{name: "cxh", sex: "man"}   對象
var obj =jQuery.parseJSON(); 
var obj = JSON.parse(str); 

JSON對象轉換為JSON字符串

var str = { "name": "cxh", "sex": "man" };

str = JSON.stringify(str ); //{name: "cxh", sex: "man"}   字符串

數組轉字符串
var arr=["a","s","d"];
var str =arr.join(',');         // a,s,d     字符串

var str=arr.toString();         //a,s,d 字符串

循環遍歷

 遍歷數組
 var arr=["a","b","c"];
　$.each(arr,function(i,item){
        console.log(i+"--"+item);
 });

 遍歷對象
  var obj={name:"xiaozhu",age:20};
  $.each(obj,function(i,item){
        console.log(i+"--"+item);
 });