How to Parse JSON Using Node.js?

javascript

json-parsing

try-catch

streaming

byNikita Barsukov·Dec 24, 2024

Use JSON.parse() in Node.js to parse JSON:

const obj = JSON.parse('{"name":"Jane","age":25}');
console.log(obj); // Outputs: { name: 'Jane', age: 25 }

To ensure character integrity, specify utf8 encoding when consuming JSON:

const fs = require('fs');

fs.readFile('path/to/json/file.json', 'utf8', (err, jsonString) => {
  if (err) {
    console.error("Read file error:", err); // Oops! Can't read? Oh, it's just a file, not a mind.
    return;
  }

  try {
    const data = JSON.parse(jsonString);
    console.log("Data:", data); // Voila! It's alive!
  } catch (err) {
    console.error("Parse error:", err); // JSON or not JSON, that is the question! 
  }
});

Safely parsing JSON and handling errors

Catch parsing mishaps with try/catch

Wrap **JSON.parse()** in a try/catch block to gracefully catch any parsing hiccups:

let jsonString = '{"invalid JSON"}';

try {
  let data = JSON.parse(jsonString);
} catch (error) {
  console.error("Parse error:", error); // It's not you, it's the JSON... 
}

Utilizing streaming for large JSON files

For larger JSON files, harness the power of streaming to parse JSON with a bigger appetite:

const { createReadStream } = require('fs');
const { parse } = require('JSONStream');

const jsonStream = createReadStream('large-file.json')
  .pipe(parse('*'));

jsonStream.on('data', (data) => {
  console.log(data); // Data, meet console. Console, meet data.
});

Secure your data

Keep your secrets by not storing sensitive data in JSON files. Remember, environment variables are your friend.

Going beyond basic parsing

Require vs JSON.parse

TURN DOWN FOR require(), turn UP for JSON.parse():

const fs = require('fs');

const data = JSON.parse(fs.readFileSync('config.json', 'utf8')); // JSON, parsed! (Airhorn noise!)

Validate data structure

Upon parsing JSON data, you should validate it like a bouncer at a nightclub to ensure it meets the expected structure:

const validateJSON = (data) => {
  // Define the schema, or "the rules of the club"
  const schema = {
    type: 'object',
    properties: {
      name: { type: 'string' },
      age: { type: 'number' }
    },
    required: ['name', 'age']
  };

  // Validate and return result
  // Just like bouncers, use a "strong" library like AJV for JSON schema validation.
};