337 lines
6.0 KiB
Markdown
337 lines
6.0 KiB
Markdown
JSON 备忘清单
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===
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这是理解和编写 JSON 格式配置文件的快速参考备忘单。
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入门
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----
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### 介绍
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[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。
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- JSON 代表 JavaScript 对象表示法
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- JSON 易于读写。
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- JSON 是与语言无关的数据交换格式
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- JSON 文件扩展名为 `.json`
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- JSON Internet 媒体类型为 `application/json`
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### 示例
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```json
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{
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"name": "Jason",
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"age": 39,
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"height": 1.92,
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"gender": "M",
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"salary": 70000,
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"married": true,
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"children": [
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{"name": "Tom", "age": 9, "gender":"M"},
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{"name": "Ava", "age": 7, "gender":"F"}
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]
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}
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```
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### 类型
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| 类型 | 描述 |
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|-----------|---------------------------------|
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| `Number` | 双精度浮点 |
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| `String` | 字符系列 |
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| `Boolean` | “true”或“false” |
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| `Array` | 有序的值序列 |
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| `Value` | 字符串、数字、布尔值、空值等 |
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| `Object` | 键/值对的无序集合 |
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| `null` | Null 或 Empty |
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### 字符串
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<!--rehype:wrap-style=grid-row: span 3/span 3;-->
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| | |
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|------|----------------------------|
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| `\"` | 双引号 Double quote |
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| `\\` | 反斜杠 Backslash |
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| `\/` | 正斜杠 Forward slash |
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| `\b` | 退格 Backspace |
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| `\f` | 换页 Form feed |
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| `\n` | 换行 Newline |
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| `\r` | 回车 Carriage return |
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| `\t` | 标签 Tab |
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| `\u` | 后跟四个十六进制数字 |
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#### 示例
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```json
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{
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"url": "https://quickref.me",
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"msg" : "Hi,\n\"QuickRef.ME\"",
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"intro": "Share quick reference and cheat sheet for developers."
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}
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```
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#### 无效字符串
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```json
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{ "foo": 'bar' }
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```
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Have to be delimited by double quotes
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### 数字
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<!--rehype:wrap-class=row-span-2-->
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类型 | 说明
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-----|------
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`Integer` | 数字 1-9、0 和正数或负数
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`Fraction` | 0.3、3.9 等分数
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`Exponent` | 指数，如 e、e+、e-、E、E+、E
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<!--rehype:className=show-header -->
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#### 示例
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```json
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{
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"positive" : 12,
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"negative" : -1,
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"fraction" : 10.25,
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"exponent" : 1.0E+2,
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"zero" : 0
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}
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```
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#### 无效的数字
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```json
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{ "foo": 0xFF }
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```
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在JSON中，只能使用十进制文字
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### 对象 Objects
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```json
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{
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"color": "Purple",
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"id": "210",
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"composition": {
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"R": 70,
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"G": 39,
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"B": 89
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},
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"empty_object": {}
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}
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```
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用逗号分隔的多个键/值对
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### 数组 Arrays
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```json
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[1, 2, 3, 4, 5]
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```
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以 `[` 开始并以 `]` 结束
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### 对象数组
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```json
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{
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"children": [
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{ "name": "Jimmy Smith", "age": 15 },
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{ "name": "Sammy Sosa", "age": 12 }
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]
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}
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```
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### 数组对象
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```json
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{
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"attributes": ["a1", "a2"],
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"methods": ["getter", "setter"],
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"empty_array": []
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}
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```
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### 二维阵列
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```json
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{
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"my_sequences": [
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[1, 2, 3],
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[4, 5, 6],
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[7, 8, 9, 0],
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[10, 11]
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]
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}
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```
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### 对象的对象
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```json
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{
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"Mark McGwire": {
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"hr": 65,
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"avg": 0.278
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},
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"Sammy Sosa": {
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"hr": 63,
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"avg": 0.288
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}
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}
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```
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### 嵌套
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```json
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{
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"Jack": {
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"id": 1,
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"name": "Franc",
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"salary": 25000,
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"hobby": ["a", "b"],
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"location": {
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"country": "A", "city": "A-A"
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}
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}
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}
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```
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在 JavaScript 中访问 JSON
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----
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### 访问对象
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```javascript
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let myObject = {
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"name": "Jason",
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"last": "Doe",
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"age": 39,
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"gender": "M",
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"salary": 70000,
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"married": true
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};
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```
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----
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|--------------------|-----------|
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| `myObject.name` | "Jason" |
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| `myObject["name"]` | "Jason" |
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| `myObject.age` | 39 |
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| `myObject.other` | undefined |
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| `myObject[0]` | undefined |
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### 访问嵌套
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<!--rehype:wrap-style=grid-row: span 2/span 2;-->
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```javascript
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let myObject = {
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"ref": {
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"name": 0,
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"last": 1,
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"age": 2,
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"gender": 3,
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"salary": 4,
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"married": 5
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},
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"jdoe": [
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"Jason",
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"Doe",
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39,
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"M",
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70000,
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true
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],
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"jsmith": [
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"Tom",
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"Smith",
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42,
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"F",
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80000,
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true
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]
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};
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```
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----
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|--------------------------|--------------------------|
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| `myObject.ref.age` | 2 |
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| `myObject["ref"]["age"]` | 2 |
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| `myObject.jdoe` | ["Jason", "Doe", 39 ...] |
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| `myObject.jsmith[3]` | "F" |
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| `myObject[1]` | undefined |
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### 访问对象数组
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<!--rehype:wrap-style=grid-row: span 2/span 2;-->
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```javascript
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let myArray = [
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{
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"name": "Jason",
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"last": "Doe",
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"age": 39,
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"gender": "M",
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"salary": 70000,
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"married": true
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},
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{
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"name": "Tom",
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"last": "Smith",
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"age": 42,
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"gender": "F",
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"salary": 80000,
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"married": true
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},
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{
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"name": "Amy",
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"last": "Burnquist",
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"age": 29,
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"gender": "F",
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"salary": 60000,
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"married": false
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}
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];
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```
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----
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|---------------------|----------------------------|
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| `myArray[0]` | `{`"name": "Jason", ...`}` |
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| `myArray[1].name` | "Tom" |
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| `myArray[1][2]` | 42 |
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| `myArray[3]` | undefined |
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| `myArray[3].gender` | TypeError: Cannot read... |
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### 访问阵列
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```javascript
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let myArray = [
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"Jason",
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"Doe",
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39,
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"M",
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70000,
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true
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];
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```
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-----
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|--------------|-----------|
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| `myArray[1]` | "Doe" |
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| `myArray[5]` | true |
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| `myArray[6]` | undefined |
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另见
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----
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- [JSON](https://www.json.org/json-en.html) _(json.org)_
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- [JSON Editor Online](http://jsoneditoronline.org/) _(jsoneditoronline.org)_
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- [Convert JSON Array to Markdown Table, CSV and more](https://tableconvert.com/json-to-markdown) _(tableconvert.com)_ |