JSON introduction

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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 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 .

Why? JSON Than XML Better ？

XML Than JSON It’s harder to parse .

JSON You can use the existing JavaScript Object parsing .

in the light of AJAX application ,JSON Than XML Data loads faster , And it’s simpler ：

Use XML

  • obtain XML file
  • Use XML DOM Iterative loop document
  • Then the data is parsed and copied to the variable

Use JSON

  • obtain JSON character string
  • JSON.Parse analysis JSON character string

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