JSON basic syntax

JSON Grammar is JavaScript A subset of grammar .

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JSON Rule of grammar

JSON Grammar is JavaScript Object represents a subset of Syntax .

• The data is in the name / Value alignment
• Data is separated by commas
• Curly braces  {}  Save the object
• brackets  []  Save array , An array can contain multiple objects

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JSON name / It's worth it

JSON The data is written in ：

key : value

name / Value pairs include field names （ In double quotes ）, Write a colon at the back , Then it's worth ：

"name" : " Novice tutorial "

It's easy to understand , Equivalent to this JavaScript sentence ：

name = " Novice tutorial "

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JSON value

JSON Values can be ：

• Numbers （ Integer or floating point number ）
• character string （ In double quotes ）
• Boolean value （true or false）
• Array （ In brackets ）
• object （ In braces ）
• null

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JSON Numbers

JSON Numbers can be integer or floating point ：

{ "age":30 }

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JSON object

JSON Objects in braces  {}  In the writing ：

{key1 : value1, key2 : value2, ... keyN : valueN }

Object can contain multiple names / It's worth it ：

{ "name":" Novice tutorial " , "url":"www.runoob.com" }

It's easy to understand , With this JavaScript Statement equivalence ：

name = " Novice tutorial " url = "www.runoob.com"

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JSON Array

JSON Array in brackets  []  In the writing ：

An array can contain multiple objects ：

[
    { key1 : value1-1 , key2:value1-2 }, 
    { key1 : value2-1 , key2:value2-2 }, 
    { key1 : value3-1 , key2:value3-2 }, 
    ...
    { key1 : valueN-1 , key2:valueN-2 }, 
]

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

In the example above , object  sites  Is an array of three objects . Each object represents a website （name、url） The record of .

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JSON Boolean value

JSON The Boolean value can be true perhaps false：

{ "flag":true }

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JSON null

JSON You can set null value ：

{ "runoob":null }

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JSON Use JavaScript grammar

because JSON Use JavaScript grammar , So no additional software is needed to handle JavaScript Medium JSON.

adopt JavaScript, You can create an array of objects , And assign values like this ：

example

var sites = [ { "name":"runoob" , "url":"www.runoob.com" }, { "name":"google" , "url":"www.google.com" }, { "name":" Microblogging " , "url":"www.weibo.com" } ];

You can visit... Like this JavaScript The first item in an array of objects （ Index from 0 Start ）：

sites[0].name;

The content returned is ：

runoob

You can modify the data like this ：

sites[0].name=" Novice tutorial ";

Try it »

 

In the next chapter , You will learn how to put JSON The text is converted to JavaScript object .

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JSON file

• JSON The file type of the file is  .json
• JSON Textual MIME The type is  application/json