【02】
JSON 语法是 JavaScript 语法的子集。
JSON 语法规则
JSON 语法是 JavaScript 对象表示法语法的子集。
JSON 名称/值对
JSON 数据的书写格式是:名称/值对。
名称/值对包括字段名称(在双引号中),后面写一个冒号,然后是值:
- "firstName":"John"
这很容易理解,等价于这条 JavaScript 语句:
- firstName ="John"
JSON 值
JSON 值可以是:
JSON 对象
JSON 对象在花括号中书写:
对象可以包含多个名称/值对:
- {"firstName":"John","lastName":"Doe"}
这一点也容易理解,与这条 JavaScript 语句等价:
- firstName ="John" lastName ="Doe"
JSON 数组
JSON 数组在方括号中书写:
数组可包含多个对象:
- {
- "employees":[
- {"firstName":"John","lastName":"Doe"},
- {"firstName":"Anna","lastName":"Smith"},
- {"firstName":"Peter","lastName":"Jones"}
- ]
- }
在上面的例子中,对象 "employees" 是包含三个对象的数组。每个对象代表一条关于某人(有姓和名)的记录。
JSON 使用 JavaScript 语法
因为 JSON 使用 JavaScript 语法,所以无需额外的软件就能处理 JavaScript 中的 JSON。
通过 JavaScript,您可以创建一个对象数组,并像这样进行赋值:
例子
- var employees =[
- {"firstName":"Bill","lastName":"Gates"},
- {"firstName":"George","lastName":"Bush"},
- {"firstName":"Thomas","lastName":"Carter"}
- ];
可以像这样访问 JavaScript 对象数组中的第一项:
- employees[0].lastName;
返回的内容是:
- Gates
可以像这样修改数据:
- employees[0].lastName ="Jobs";
JSON 文件

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