JSON.stringify() in JavaScript

What is JSON.stringify()?

• JSON.stringify() is a built-in JavaScript method.

• It converts a JavaScript object or value into a JSON string.

• Useful when you want to send data to a server or save it as text.

Syntax

JSON.stringify(value[, replacer[, space]])

• value: The JavaScript object or value to convert.

• replacer (optional): A function or array that alters how objects and values are stringified.

• space (optional): Adds indentation, white space, and line breaks to make the output more readable.

Basic Example

const obj = {  name: "John",  age: 30,  city: "New York"};const jsonString = JSON.stringify(obj);console.log(jsonString);// Output: '{"name":"John","age":30,"city":"New York"}'

Using the replacer Parameter

As a function to filter or transform values:

const obj = {  name: "John",  age: 30,  city: "New York"};const jsonString = JSON.stringify(obj, (key, value) => {  if (typeof value === "number") {    return undefined;  // exclude numbers  }  return value;});console.log(jsonString);// Output: '{"name":"John","city":"New York"}'

As an array to include only specific keys:

const jsonString = JSON.stringify(obj, ["name", "city"]);console.log(jsonString);// Output: '{"name":"John","city":"New York"}'

Using the space Parameter

Makes the JSON output pretty-printed (human-readable):

const jsonString = JSON.stringify(obj, null, 4);console.log(jsonString);/* Output:{    "name": "John",    "age": 30,    "city": "New York"}*/

Summary

If you want, I can help you with examples of converting complex objects or handling circular references!