Detailed explanation of json file writing format

What is JSON

JSON (JavaScript Object Notation) is a data exchange format.

Why this technology?

Before Json, everyone used XML to transfer data. XML is a plain text format, so it is suitable for exchanging data on the Internet, but the XML format is relatively complex. Finally, Douglas Crockford invented JSON, an ultra-lightweight data exchange format.

How to use JSON

- Data format

JSON is actually a subset of JavaScript, so the data format of JSON corresponds to JavaScript:

- number => JS number 
- boolean => JS boolean
- string => JS string //
- null => JS null 
- array => JS Array expression []
- object => JS {} expression

- Notes

• JSON specifies that the character set is UTF-8, strings must use "", and Object keys must also use ""
• The last member of an array or object cannot have a comma

- JS has two built-in Json methods

JSON.stringify( {} , [ ] , "")
//Parameter 1: data to be serialized (object)
//Parameter 2: Control the key value of the object. If you only want to output the specified attributes, pass in an array. //Parameter 3: After serialization, print the output format (a Tab to view json more intuitively)

Any conversion of JavaScript to Json means serializing the object into a Json string before it can be transmitted over the network;

Receive a string in Json format.

JSON.parse( json.DATA ) // Pass in the json string

If we receive a string in JSON format, we just need to deserialize it into a JavaScript object and then use it directly in JavaScript.

Examples:

1. Array method [ ]

[{
"id" : 1 ,
"name" : "xiaoming"
},{
"id" : 2 , 
"name" : "xiaohong"
}]

2. Object method { }

//Separate the front-end and back-end, it is recommended that the back-end return data to the front-end in the format {
"status" : 0 , //Execution status code "msg" : "SUCCESS", //Description text information, not NULL
"data" :[{ //The array is nested in the object, the array is the returned data,
"id" : 1 ,
"name" : "xiaohong"
},{
"id" : 2,
"name" : "xiaoming"
}]
}

3. Counterexample

{"id" : ox16 } // Illegal, the value must be in decimal {"name" : underfined } // Illegal, no such value [{
"name" : NUll,
"school" : function() {
console.log("This is wrong")
}//Illegal}]//User-defined functions or system built-in functions cannot be used in json

This concludes this article on the detailed explanation of the json file writing format. I hope it will be helpful for everyone’s study, and I also hope that everyone will support 123WORDPRESS.COM.