JSON 备忘清单
===
这是理解和编写 JSON 格式配置文件的快速参考备忘单。
入门
----
### 介绍
[JSON](https://json.org/) 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`
### 示例
```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
| 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 |
### 字符串
<!--rehype:wrap-style=grid-row: span 3/span 3;-->
| | |
|------|----------------------------|
| `\"` | 双引号 Double quote |
| `\\` | 反斜杠 Backslash |
| `\/` | 正斜杠 Forward slash |
| `\b` | 退格 Backspace |
| `\f` | 换页 Form feed |
| `\n` | 换行 Newline |
| `\r` | 回车 Carriage return |
| `\t` | 标签 Tab |
| `\u` | 后跟四个十六进制数字 |
#### 示例
```json
{
"url": "https://jaywcjlove.github.io",
"msg" : "Hi,\n\"Quick Reference\"",
"intro": "为开发人员分享快速参考和备忘单"
}
```
#### 无效字符串
```json
{ "foo": 'bar' }
```
Have to be delimited by double quotes
### 数字
<!--rehype:wrap-class=row-span-2-->
类型 | 说明
-----|------
`Integer` | 数字 1-9、0 和正数或负数
`Fraction` | 0.3、3.9 等分数
`Exponent` | 指数，如 e、e+、e-、E、E+、E
<!--rehype:className=show-header -->
#### 示例
```json
{
"positive" : 12,
"negative" : -1,
"fraction" : 10.25,
"exponent" : 1.0E+2,
"zero" : 0
}
```
#### 无效的数字
```json
{ "foo": 0xFF }
```
在JSON中，只能使用十进制文字
### 对象 Objects
```json
{
"color": "Purple",
"id": "210",
"composition": {
"R": 70,
"G": 39,
"B": 89
},
"empty_object": {}
}
```
用逗号分隔的多个键/值对
### 数组 Arrays
```json
[1, 2, 3, 4, 5]
```
以 `[` 开始并以 `]` 结束
### 对象数组
```json
{
"children": [
{ "name": "Jimmy Smith", "age": 15 },
{ "name": "Sammy Sosa", "age": 12 }
]
}
```
### 数组对象
```json
{
"attributes": ["a1", "a2"],
"methods": ["getter", "setter"],
"empty_array": []
}
```
### 二维阵列
```json
{
"my_sequences": [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9, 0],
[10, 11]
]
}
```
### 对象的对象
```json
{
"Mark McGwire": {
"hr": 65,
"avg": 0.278
},
"Sammy Sosa": {
"hr": 63,
"avg": 0.288
}
}
```
### 嵌套
```json
{
"Jack": {
"id": 1,
"name": "Franc",
"salary": 25000,
"hobby": ["a", "b"],
"location": {
"country": "A", "city": "A-A"
}
}
}
```
JSON 5
----
### Objects
对象键可以是 ECMAScript 5.1 [IdentifierName](https://www.ecma-international.org/ecma-262/5.1/#sec-7.6)
```json
{
width: 1920,
height: 1080,
}
```
数组可以有一个尾随逗号
```json
[
1,
true,
'three',
]
```
### 允许单行和多行注释
```js
{
// 一行注释
"name": "Kenny"
}
```
多行注释
```js
{
/* 这是一个
多行注释 */
"name": "Kenny"
}
```
### 允许附加空白字符
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
<!--rehype:className=left-align-->
### 数字
数字可能有前导或尾随小数点
```json
{
integer: 123,
withFractionPart: 123.456,
onlyFractionPart: .456,
withExponent: 123e-456,
}
```
数字可以是十六进制
```json
{
positiveHex: 0xdecaf,
negativeHex: -0xC0FFEE,
}
```
数字可以是正无穷大、负无穷大和 NaN。
```json
{
positiveInfinity: Infinity,
negativeInfinity: -Infinity,
notANumber: NaN,
}
```
数字可以以明确的加号开头
### 字符串
<!--rehype:wrap-class=col-span-2-->
```js
'Lorem ipsum dolor sit amet, \
consectetur adipiscing elit.'
```
以下是代表相同的意思
```js
'Lorem ipsum dolor sit amet, consectetur adipiscing elit.'
```
```json
'\A\C\/\D\C'
```
以下是代表相同的意思
```json
'AC/DC'
```
在 JavaScript 中访问 JSON
----
### 访问对象
```javascript
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 |
### 访问嵌套
<!--rehype:wrap-style=grid-row: span 2/span 2;-->
```javascript
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 |
### 访问对象数组
<!--rehype:wrap-style=grid-row: span 2/span 2;-->
```javascript
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... |
### 访问阵列
```javascript
let myArray = [
"Jason",
"Doe",
39,
"M",
70000,
true
];
```
----
| | |
|--------------|-----------|
| `myArray[1]` | "Doe" |
| `myArray[5]` | true |
| `myArray[6]` | undefined |
另见
----
- [JSON](https://www.json.org/json-en.html) _(json.org)_
- [JSON Editor Online](http://jsoneditoronline.org/) _(jsoneditoronline.org)_
- [Convert JSON Array to Markdown Table, CSV and more](https://tableconvert.com/json-to-markdown) _(tableconvert.com)_