JSON、遍历获取json对象的值

一、JSON基本入门

二、定义JSON对象

建一个html:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        //1.定义基本格式
        var person = {"name": "张三", age: 23, 'gender': true};

        //获取name的值
        //var name = person.name;
        var name = person["name"];
       // alert(name);

        //alert(person);
        //2.嵌套格式   {}———> []
        var persons = {
            "persons": [
                {"name": "张三", "age": 23, "gender": true},
                {"name": "李四", "age": 24, "gender": true},
                {"name": "王五", "age": 25, "gender": false}
                ]
        };
       // alert(persons);
        //获取王五值
        var name1 = persons.persons[2].name;
       // alert(name1);


        //2.嵌套格式   []———> {}
        var ps = [{"name": "张三", "age": 23, "gender": true},
            {"name": "李四", "age": 24, "gender": true},
            {"name": "王五", "age": 25, "gender": false}];
        //获取李四值
        //alert(ps);
        alert(ps[1].name);


    </script>

</head>
<body>

</body>
</html>

三、遍历获取json对象的值:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>JSON遍历</title>
    <script>
        //定义json(基本格式),键可以+引号也可以不加
        var person={"name":"张三",age:23,"gender":true};

        //2.嵌套格式(数组里面有json对象)   []———> {}
        var ps=[{"name":"张三",age:23,"gender":true},
            {"name":"王五",age:24,"gender":true},
            {"name":"李四",age:25,"gender":false}];

        //3.嵌套格式(json对象里面有数组)   {}———> []
        var persons = {
            "p": [
                {"name": "张三2", "age": 23, "gender": true},
                {"name": "李四2", "age": 24, "gender": true},
                {"name": "王五2", "age": 25, "gender": false}
            ]};

        //1.获取person(基本格式)对象中所有的键和值
        //for in 循环,key是json对象的键，对象.键名这里遍历不管用，要对象[键]才行
        for (var key in person){
            //这样的方式获取不行。因为相当于  person."name"
            //alert(key + ":" + person.key);
            alert(key+":"+person[key]);
        }

        // 2.遍历数组里面的json(重点)
        //获取ps中的所有值,先遍历数组
        for(var i=0;i<ps.length;i++){
            //获取数组里面的每一个json对象
            var p=ps[i];
            for (var key in p){
                alert(key+":"+p[key]);
            }
        }

        // 3.遍历json里面的数组
        for (var key1 in persons){
            var json_value_array=persons[key1];
            for (var i=0;i<json_value_array.length;i++){
                //获取数组里面的每一个json对象
                var pi=json_value_array[i];
                for (var key2 in pi){
                    alert(key2+":"+pi[key2]);
                }
            }
        }

    </script>
</head>
<body>


</body>
</html>