JSON. Stringify() and JSON parse()

First understand JSON and JS Relationship of objects
JSON:let str = ‘{“a”:“test”,“b”:123}’ // This is a JSON character string , The essence is a string
JS object ：let str = { a: ‘test’, b: 123 } // This is an object , Note that key names can also be enclosed in quotation marks

JSON yes JS String representation of object , It uses text to represent a JS Object information , The essence is a string .

• JSON.stringify() ： take JS Object to JSON Format

 ` //  The test case 1：
let str = {
    a: 'test', b: 123};
console.log('-----------str:', JSON.stringify(str));
-----------str: {
    "a":"test","b":123}

• JSON.parse() ： take JSON Converts a string to an object

//  The test case 1：
let str = '{"a":"test","b":123}';
console.log('----------str :', JSON.parse(str ));
----------str : {
     a: 'test', b: 123 }

let str2 = [1, 2, 3];
let str3 = JSON.stringify(str2); // '[1,2,3]'
let str4 = JSON.parse(str3); // [1,2,3]
console.log('-----------str3:', str3, typeof str3);
console.log('-----------str4:', str4, typeof str4);

-----------str3: [1,2,3] string
-----------str4: [ 1, 2, 3 ] object