JSON

JSON

JSON全称JavaScript Object Notation(JavaScript 对象表示法)，JSON语法可以有三种类型的值，分别是简单值（字符，数字，布尔值和null），对象和数组。

JSON解析与序列化

JSON对象的两个方法：

stringify():把JavaScript对象序列化为JSON字符串。

parse()：把JSON字符串解析为原生JavaScript值

var book = {
               "title": "Professional JavaScript",
                "authors": [
                    "Nicholas C. Zakas"
                ],
                edition: 3,
                year: 2011
           };

var jsonText = JSON.stringify(book);
alert(jsonText);//结果：{"title":"Professional JavaScript","authors":["Nicholas C. Zakas"],"edition":3,"year":2011}
        
var bookCopy = JSON.parse(jsonText);
alert(bookCopy.title);//结果：Professional JavaScript

JSON.stringify()除了JavaScript对象外，还可以接受第二个参数，可以是数组或者函数

var book = {
                title: "Professional JavaScript",
                authors: [
                    "Nicholas C. Zakas"
                ],
                edition: 3,
                year: 2011
           };

var jsonText = JSON.stringify(book, ["title", "edition"]);//参数：数组，起过滤作用
alert(jsonText);

var book = {
                title: "Professional JavaScript",
                authors: [
                    "Nicholas C. Zakas"
                ],
                edition: 3,
                year: 2011
           };

var jsonText = JSON.stringify(book, function(key, value){//参数：函数，将在每个键值对上调用
    switch(key){
        case "authors":
            return value.join(",")
                 
        case "year":
            return 5000;
                    
        case "edition":
            return undefined;
                    
        default:
            return value;
    }
});
alert(jsonText);

JSON.parse()方法接收一个参数，该参数是一个函数，将在每个键值对上调用

var book = {
               "title": "Professional JavaScript",
                "authors": [
                    "Nicholas C. Zakas"
                ],
                edition: 3,
                year: 2011,
                releaseDate: new Date(2011, 11, 1)
           };

var jsonText = JSON.stringify(book);
alert(jsonText);
        
var bookCopy = JSON.parse(jsonText, function(key, value){
    if (key == "releaseDate"){
        return undefined;
    } else {
        return value;
    }
});
        
alert("releaseDate" in bookCopy);