[JavaScript基础]学习②③--JSON

JSON的数据类型

number：

boolean：

string：

null：

array：[]

object：{ ... }

JSON的字符串规定必须用双引号""，Object的键也必须用双引号""

序列化

var xiaoming = {
    name: '小明',
    age: 14,
    gender: true,
    height: 1.65,
    grade: null,
    'middle-school': '\"W3C\" Middle School',
    skills: ['JavaScript', 'Java', 'Python', 'Lisp']
};

JSON.stringify(xiaoming); // '{"name":"小明","age":14,"gender":true,"height":1.65,"grade":null,"middle-school":"\"W3C\" Middle School","skills":["JavaScript","Java","Python","Lisp"]}'

缩进输出

JSON.stringify(xiaoming, null, '  ');

{
  "name": "小明",
  "age": 14,
  "gender": true,
  "height": 1.65,
  "grade": null,
  "middle-school": "\"W3C\" Middle School",
  "skills": [
    "JavaScript",
    "Java",
    "Python",
    "Lisp"
  ]
}  

输出指定的属性

JSON.stringify(xiaoming, ['name', 'skills'], '  ');

{
  "name": "小明",
  "skills": [
    "JavaScript",
    "Java",
    "Python",
    "Lisp"
  ]
}

传入一个函数

function convert(key, value) {
    if (typeof value === 'string') {
        return value.toUpperCase();
    }
    return value;
}

JSON.stringify(xiaoming, convert, '  ');

{
  "name": "小明",
  "age": 14,
  "gender": true,
  "height": 1.65,
  "grade": null,
  "middle-school": "\"W3C\" MIDDLE SCHOOL",
  "skills": [
    "JAVASCRIPT",
    "JAVA",
    "PYTHON",
    "LISP"
  ]
}

定义一个toJSON()的方法，直接返回JSON应该序列化的数据

var xiaoming = {
    name: '小明',
    age: 14,
    gender: true,
    height: 1.65,
    grade: null,
    'middle-school': '\"W3C\" Middle School',
    skills: ['JavaScript', 'Java', 'Python', 'Lisp'],
    toJSON: function () {
        return { // 只输出name和age，并且改变了key：
            'Name': this.name,
            'Age': this.age
        };
    }
};

JSON.stringify(xiaoming); // '{"Name":"小明","Age":14}'

反序列化

JSON.parse() 转化为JavaScript对象

JSON.parse('[1,2,3,true]'); // [1, 2, 3, true]
JSON.parse('{"name":"小明","age":14}'); // Object {name: '小明', age: 14}
JSON.parse('true'); // true
JSON.parse('123.45'); // 123.45
alert(JSON.parse('{"name":"小明","age" :14}').name);//小明

转换解析出的属性

JSON.parse('{"name":"小明","age":14}', function (key, value) {
    // 把number * 2:
    if (key === 'name') {
        return value + '同学';
    }
    return value;
}); // Object {name: '小明同学', age: 14}