JSON.parse()

Data received from a web server is always a string. To use this data as a JavaScript object, you must convert it. The JSON.parse() method parses a JSON string and returns a JavaScript object.

String to Object Laboratory

Try parsing the JSON text below. Notice how the status changes from "String" to "JavaScript Object Property":

Basic Example

Imagine we receive this text from a web server:

let text = '{"name":"John", "age":30, "city":"New York"}';

Use JSON.parse() to convert it into a JavaScript object:

let obj = JSON.parse(text);

// Now you can access it like an object
console.log(obj.name); // John

Parsing Dates

JSON does not allow date objects. If you need to include a date, write it as a string. You can convert it back into a date object later using the reviver function (the second parameter of JSON.parse).

let text = '{"name":"John", "birth":"1986-12-14"}';
let obj = JSON.parse(text, function (key, value) {
  if (key == "birth") {
    return new Date(value);
  } else {
    return value;
  }
});

console.log(obj.birth.getFullYear()); // 1986

Browser Support

The JSON.parse() method is part of all modern browsers and the ECMAScript 5 (ES5) standard.

Key Points to Remember

• JSON.parse() converts a string into a JS object.
• The input string must be **valid JSON**.
• It is used to handle data fetched from APIs/Servers.
• Use the **reviver** function to transform values (like dates) during parsing.
• It is the secure way to convert text to objects.