JSON 备忘清单

JSON 是一种基于文本的轻量级开放标准，专为人类可读的数据交换而设计。

• JSON 代表 JavaScript 对象表示法
• JSON 易于读写。
• JSON 是与语言无关的数据交换格式
• JSON 文件扩展名为 .json
• JSON Internet 媒体类型为 application/json

{
  "name": "Jason",
  "age": 39,
  "height": 1.92,
  "gender": "M",
  "salary": 70000,
  "married": true,
  "children": [
    {"name": "Tom", "age": 9},
    {"name": "Ava", "age": 7}
  ]
}

类型	描述
Number	双精度浮点
String	字符系列
Boolean	“true”或“false”
Array	有序的值序列
Value	字符串、数字、布尔值、空值等
Object	键/值对的无序集合
null	Null 或 Empty

{
  "color": "Purple",
  "id": "210",
  "composition": {
    "R": 70,
    "G": 39,
    "B": 89
  },
  "empty_object": {}
}

用逗号分隔的多个键/值对

[1, 2, 3, 4, 5]

以 [ 开始并以 ] 结束

{
  "children": [
    { "name": "Jimmy Smith", "age": 15 },
    { "name": "Sammy Sosa", "age": 12 }
  ]
}

{
  "attributes": ["a1", "a2"],
  "methods": ["getter", "setter"],
  "empty_array": []
}

{
  "my_sequences": [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9, 0],
    [10, 11]
  ]
}

{
  "Mark McGwire": {
    "hr": 65,
    "avg": 0.278
  },
  "Sammy Sosa": {
    "hr": 63,
    "avg": 0.288
  }
}

{
  "Jack": {
    "id": 1,
    "name": "Franc",
    "salary": 25000,
    "hobby": ["a", "b"],
    "location": {
        "country": "A", "city": "A-A"
    }
  }
}

对象键可以是 ECMAScript 5.1 IdentifierName

{
    width: 1920,
    height: 1080,
}

数组可以有一个尾随逗号

[
    1,
    true,
    'three',
]

{
  // 一行注释
  "name": "Kenny"
}

多行注释

{
/* 这是一个
   多行注释 */
  "name": "Kenny"
}

代码点	描述
U+0009	水平制表符
U+000A	换行符
U+000B	垂直制表符
U+000C	换页符
U+000D	回车符
U+0020	空格
U+00A0	不间断空格
U+2028	行分隔符
U+2029	段落分隔符
U+FEFF	字节顺序标记
Unicode Zs 类别	空格分隔符 Unicode 类别中的任何其他字符

数字可能有前导或尾随小数点

{
    integer: 123,
    withFractionPart: 123.456,
    onlyFractionPart: .456,
    withExponent: 123e-456,
}

数字可以是十六进制

{
    positiveHex: 0xdecaf,
    negativeHex: -0xC0FFEE,
}

数字可以是正无穷大、负无穷大和 NaN。

{
    positiveInfinity: Infinity,
    negativeInfinity: -Infinity,
    notANumber: NaN,
}

数字可以以明确的加号开头

let myObject = {
  "name": "Jason",
  "last": "Doe",
  "age": 39,
  "gender": "M",
  "salary": 70000,
  "married": true
};

---

myObject.name	"Jason"
myObject["name"]	"Jason"
myObject.age	39
myObject.other	undefined
myObject[0]	undefined

let myObject = {
    "ref": {
        "name": 0,
        "last": 1,
        "age": 2,
        "gender": 3,
        "salary": 4,
        "married": 5
    },
    "jdoe": [
        "Jason",
        "Doe",
        39,
        "M",
        70000,
        true
    ],
    "jsmith": [
        "Tom",
        "Smith",
        42,
        "F",
        80000,
        true
    ]
};

---

myObject.ref.age	2
myObject["ref"]["age"]	2
myObject.jdoe	["Jason", "Doe", 39 ...]
myObject.jsmith[3]	"F"
myObject[1]	undefined

let myArray = [
  {
    "name": "Jason",
    "last": "Doe",
    "age": 39,
    "gender": "M",
    "salary": 70000,
    "married": true
  },
  {
    "name": "Tom",
    "last": "Smith",
    "age": 42,
    "gender": "F",
    "salary": 80000,
    "married": true
  },
  {
    "name": "Amy",
    "last": "Burnquist",
    "age": 29,
    "gender": "F",
    "salary": 60000,
    "married": false
  }
];

---

myArray[0]	{"name": "Jason", ...}
myArray[1].name	"Tom"
myArray[1][2]	42
myArray[3]	undefined
myArray[3].gender	TypeError: Cannot read...

let myArray = [
  "Jason",
  "Doe",
  39,
  "M",
  70000,
  true
];

---

myArray[1]	"Doe"
myArray[5]	true
myArray[6]	undefined