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JSON introduction

2022-06-26 01:27:00 【Life needs depth】

JSON course

JSON: JavaScript Object Notation(JavaScript Object notation )

JSON Is the syntax for storing and exchanging text information , similar XML.

JSON Than XML smaller 、 faster , Easier to parse .

JSON example

{ "sites": [ { "name":" Novice tutorial " , "url":"www.runoob.com" }, { "name":"google" , "url":"www.google.com" }, { "name":" Microblogging " , "url":"www.weibo.com" } ] }

This sites The object is to contain 3 Site records （ object ） Array of .

What is? JSON ？

JSON refer to JavaScript Object notation （JavaScript Object Notation）
JSON It's a lightweight text data exchange format
JSON Independent of language ：JSON Use Javascript Syntax to describe data objects , however JSON Still independent of language and platform .JSON Parser and JSON The library supports many different programming languages . There's a lot of movement right now （PHP,JSP,.NET） Programming languages support JSON.
JSON Be self descriptive , Easier to understand

JSON - Convert to JavaScript object

JSON Text format in syntax and create JavaScript The code of the object is the same .

Because of this similarity , No parser required ,JavaScript The program can use built-in eval() function , use JSON Data to generate native JavaScript object .

Online examples

Through our editor , You can edit it online JavaScript Code , Then click a button to see the results ：

JSON example

<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title> Novice tutorial (runoob.com)</title> </head> <body> <h2>JavaScript establish JSON object </h2> <p> Website name : <span id="jname"></span><br /> Web site address : <span id="jurl"></span><br /> Website slogan: <span id="jslogan"></span><br /> </p> <script>

var JSONObject= { "name":" Novice tutorial ", "url":"www.runoob.com", "slogan":" It's not just technology that you learn , Is the dream ！" }; document.getElementById("jname").innerHTML=JSONObject.name document.getElementById("jurl").innerHTML=JSONObject.url document.getElementById("jslogan").innerHTML=JSONObject.slogan

</script> </body> </html>

Try it »
Click on " Try it " Button to view the online instance .

And XML Similarities

JSON Is the plain text
JSON have " self-description "（ Human readable ）
JSON It has a hierarchy （ There is a value in the value ）
JSON It can be done by JavaScript To analyze
JSON Data available AJAX transmitted

And XML The difference

No end tag
shorter
Faster reading and writing
Be able to use built-in JavaScript eval() Method
Using arrays
Reserved words are not used

Why use JSON？

about AJAX For applications ,JSON Than XML Faster and easier to use ：

Use XML

Read XML file
Use XML DOM To loop through the document
Read the value and store it in the variable

Use JSON

Read JSON character string
use eval() Handle JSON character string

JSON vs XML

JSON and XML All for receiving web Data on the server .

JSON and XML There are differences in writing , As shown below ：

JSON example

{ "sites": [ { "name":" Novice tutorial " , "url":"www.runoob.com" }, { "name":"google" , "url":"www.google.com" }, { "name":" Microblogging " , "url":"www.weibo.com" } ] }

XML example

<sites> <site> <name> Novice tutorial </name> <url>www.runoob.com</url> </site> <site> <name>google</name> <url>www.google.com</url> </site> <site> <name> Microblogging </name> <url>www.weibo.com</url> </site> </sites>

JSON And XML The similarities ：

JSON and XML The data are all " Self description " , Are easy to understand .
JSON and XML The data has a hierarchical structure
JSON and XML Data can be used by most programming languages

JSON And XML The difference ：

JSON There is no need to end the tag
JSON Shorter
JSON Faster reading and writing
JSON You can use arrays

The biggest difference is ：XML Need to use XML Parsers to parse ,JSON You can use standard JavaScript Function to parse .
JSON.parse(): Will a JSON String conversion to JavaScript object .
JSON.stringify(): At will JavaScript Value to JSON character string .