Description

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Intermediate · 12 min

Read and write JSON

Convert between JSON text and JavaScript values, then validate the shape.

Parse JSON text

JSON.parse() reads JSON text. Valid JSON does not guarantee the shape your program expects, so check important fields before using them.

const text = '{"name":"Ada","sessions":3}';
const user = JSON.parse(text);
console.log(user.name);
console.log(user.sessions);

Output

Ada
3

Serialize a value

JSON.stringify() creates JSON text. JSON does not represent functions or undefined values, so it is not a general-purpose clone for every JavaScript object.

const settings = { theme: "dark", reminders: true };
console.log(JSON.stringify(settings));

Output

{"theme":"dark","reminders":true}

Put it into practice

  1. Predict each result before running the example.
  2. Complete the coding task, then explain why your solution works.

Try it yourself

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Summarize JSON data

Parse text and add its numeric values. Store the result in total and display it.

Practice