1.json
json是一种语法,用来存储和交换数据的语法;用javascript对象标记方法书写的文本格式
浏览器中javascript对象----->转化为----->json文本发送到服务器 (反之亦然)
简化了复杂的数据解析
2.用法
js对象和json对象之间转化:
1.javascript中创建的对象,利用json对象的方法封装成json格式的数据文本/字符串
var myObj = { name:"Bill Gates", age:62, city:"Seattle" }; var myJSON = JSON.stringify(myObj); window.location = "demo_json.php?x=" + myJSON;
2.var myObj = JSON.parse(myJSON); //将接收的json转化为js数组
使用这个内部函数时,json的格式必须是这种‘{“xx”:"xx" }’
var myJSON= '{
"employees":['
+'{"firstName":"Bill","lastName":"Gates" },'
+ '{"firstName":"Steve","lastName":"Jobs" },'
+'{"firstName":"Elon","lastName":"Musk" }
]
}'
ps:一个对象:
"cars": [ { "name":"Porsche", "models":[ "911", "Taycan" ] }, { "name":"BMW", "models":[ "M5", "M3", "X5" ] }, { "name":"Volvo", "models":[ "XC60", "V60" ] } ]
3.可以存到本地变量再取出:
localStorage.setItem("testJSON", myJSON); text = localStorage.getItem("testJSON");
4.区别:js对象和json数据:
var myObj = { name:"Bill Gates", age:62, city:"Seattle" };
var myJSON = { "name":"Bill Gates", "age":62, "city":"Seattle" };
3.json数据类型:
在 JSON 中,值必须是以下数据类型之一:
- 字符串“”
- 数字必须是整数或浮点数
- 对象(JSON 对象)
{ "employee":{ "name":"Bill Gates", "age":62, "city":"Seattle" } }
- 数组
{ "employees":[ "Bill", "Steve", "David" ] }
与js数组一样
"cars":[ "Porsche", "BMW", "Volvo" ]
- 布尔
- Null