How to Fetch Data from Json File in Node JS

In Node.js, you can fetch data from a JSON file using the built-in fs (file system) module. Here’s an example of how you can read data from a JSON file:

1. First, require the fs module:

const fs = require('fs');

2. Next, use the fs.readFile() method to read the contents of the JSON file. This method takes two parameters: the path to the file and a callback function that will be called when the file is read. The callback function takes two parameters: an error (if one occurred) and the contents of the file.

fs.readFile('path/to/your/file.json', (err, data) => {
  if (err) throw err;

  // do something with the data
});

3. Once the file has been read, you can parse the JSON data using JSON.parse(). This method takes a JSON string and converts it into a JavaScript object.

fs.readFile('path/to/your/file.json', (err, data) => {
  if (err) throw err;

  const jsonData = JSON.parse(data);

  // do something with the jsonData object
});

4. Finally, you can use the data in your application as needed.

Here’s the complete code to fetch data from a JSON file:

const fs = require('fs');

fs.readFile('path/to/your/file.json', (err, data) => {
  if (err) throw err;

  const jsonData = JSON.parse(data);

  console.log(jsonData); // log the data to the console
});

Suppose we have a data.json file with the following content:

{
  "name": "John Doe",
  "age": 30,
  "address": {
    "street": "123 Main St",
    "city": "Anytown",
    "state": "CA",
    "zip": "12345"
  },
  "phoneNumbers": [
    {
      "type": "home",
      "number": "555-555-1234"
    },
    {
      "type": "work",
      "number": "555-555-5678"
    }
  ]
}

To fetch the data from this file, we can use the following code:

const fs = require('fs');

fs.readFile('data.json', (err, data) => {
  if (err) throw err;

  const jsonData = JSON.parse(data);

  console.log(jsonData.name); // output: John Doe
  console.log(jsonData.age); // output: 30
  console.log(jsonData.address.street); // output: 123 Main St
  console.log(jsonData.phoneNumbers[0].number); // output: 555-555-1234
});

In this example, we first require the fs module and then use the fs.readFile() method to read the contents of the data.json file. We pass in a callback function that takes an error (if one occurred) and the contents of the file.

Inside the callback function, we use the JSON.parse() method to convert the JSON data into a JavaScript object. We can then access the properties of the object as needed. In this example, we log the values of the name, age, address.street, and phoneNumbers[0].number properties to the console.