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What is JSON? First acquaintance with JSON

2022-04-23 05:46:00 【DK_ ten thousand and thirty-two】

Learning goals ：

Can skillfully use in development JSON Format storage data 、 How to access the JSON data

JSON The definition of ：

        JSON (JavaScript Object Notation) yes ⼀ A lightweight data exchange format . Easy to ⼈ Read and write . It's also easy to machine analyze and ⽣ become . It's based on JavaScript Programming Language, Standard ECMA-262 3rd Edition -December 1999 Of ⼀ individual ⼦ Set . JSON Mining ⽤ Totally alone ⽴ Yu Yu ⾔ Of ⽂ This format , But it also makes ⽤ It's similar to C language ⾔ Family habits （ Include C, C++, C#, Java, JavaScript, Perl, Python etc. ）. These characteristics make JSON Become an ideal data exchange language ⾔.

         In standard json In the format ,json Objects are enclosed in parentheses , The properties in the object are json Of key yes ⼀ A string , therefore ⼀ Make sure that ⽤ Double quotation marks . Each group key Between ⽤ Comma in ⾏ Separate .

Json Define format ：

var  Variable name  = {
    
	"key1" : value , 		// Number type 
	"key2"  : "value" , 	//  String type 
	"key3"  : [] ,		 	//  An array type 
	"key4" : {
    }, 			// json  object type 
	"key5" : [{
    },{
    }] 		// json  Array 
};

JSON Object access ：

        json object , seeing the name of a thing one thinks of its function , I know it is ⼀ Objects .⾥⾯ Of key It's the properties of the object . We are going to visit ⼀ Properties of an object ,
         Just make ⽤【 Object name . Property name 】 Of ⽅ It's easy to access .
for example ：

    <script type="text/javascript"> // 1. Definition JSON var j1 = {
      "name":" Zhang San ","age":18}; alert(j1.name+","+j1.age); //  Zhang San ,18 //  Array  var j2 = {
      "names":["aa","bb","cc"]} alert(j2.names[1]); // bb //json  An array of content  var j3 = {
      "users":[{
      "name":" Zhang San ","age":18},{
      "name":" Zhang San 2","age":14},{
      "name":" Zhang San 3","age":12}]}; alert(j3.users[0].name); //  Zhang San  </script>

The following is the page source code , Save as *.html Open the page with a browser , You can see the result directly 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>JSONTest</title>
    <script type="text/javascript"> // 1. Definition JSON var j1 = {
      "name":" Zhang San ","age":18}; alert(j1.name+","+j1.age); //  Zhang San ,18 //  Array  var j2 = {
      "names":["aa","bb","cc"]} alert(j2.names[1]); // bb //json  An array of content  var j3 = {
      "users":[{
      "name":" Zhang San ","age":18},{
      "name":" Zhang San 2","age":14},{
      "name":" Zhang San 3","age":12}]}; alert(j3.users[0].name); //  Zhang San  </script>
</head>
<body>
    <h1> JSON  Study </h1>
</body>
</html>

版权声明
本文为[DK_ ten thousand and thirty-two]所创，转载请带上原文链接，感谢
https://yzsam.com/2022/04/202204220534093892.html

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