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2.5 JSON

2.5.1.JSON格式的用途

• 在开发中凡是涉及到『跨平台数据传输』，JSON格式一定是首选

2.5.2.JSON格式的说明

• 1.JSON数据两端要么是{}，要么是[]
  • {}定义JSON对象
  • []定义JSON数组
• 2.JSON对象的格式是：json {key:value,key:value,...,key:value}
• 3.JOSN数组的格式是：[value,value,...,value]
  • key的类型固定是字符串
  • value的类型可以是：
    • 基本数据类型
    • 引用类型：JSON对象或JSON数组
• 4.正因为JSON格式中value部分还可以继续使用JSON对象或JSON数组，所以JSON格式是可以『多层嵌套，所以JSON格式不论多么复杂的数据类型都可以表达。

//json的格式: {key:value,key:value}
var person1 = {"name":"张三疯","age":189,"address":"武当山"
}
//其实JSON对于前端而言，就是一个对象
//console.log(person1.name)
var person2 = {"name":"张三疯","age":189,"address":"武当山","wife":{"name":"小花","age":18,"address":"武当山下的小村庄"}
}
//console.log(person2.wife.name)
var person3 = {"name":"张三疯","age":189,"address":"武当山","wife":{"name":"小花","age":18,"address":"武当山下的小村庄"},"sons":[{"name":"奥巴马","age":1,"address":"武当山"},{"name":"奥拉夫","age":2,"address":"少林寺"}]
}//json数组的格式: [{key:value,key:value},{key:value,key:value}]
//var personList = [person1,person2]

• 5.JSON对象和JSON字符串互转
• JSON对象转JSON字符串

var jsonObj = {"stuName":"tom","stuAge":20};
var jsonStr = JSON.stringify(jsonObj);
console.log(typeof jsonObj); // object
console.log(typeof jsonStr); // string

• JSON字符串转JSON对象

jsonObj = JSON.parse(jsonStr);
console.log(jsonObj); // {stuName: "tom", stuAge: 20}

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