What is JSONJSON (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 formatJSON 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
- JS has two built-in Json methodsJSON.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. You may also be interested in:
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