Sending a JSON file to Express server using JS

Another option is to use sendFile and set the content type header.

app.get('/search', (req, res) => {
    res.header("Content-Type",'application/json');
    res.sendFile(path.join(__dirname, 'file_name.json'));
})

The code assumes the file is in the same directory as the JS code. This answer explains how this works.

Just make sure you're requiring the correct file as a variable and then pass that variable into your res.send!

const data = require('/path/to/data.json')

app.get('/search', function (req, res) {
  res.header("Content-Type",'application/json');
  res.send(JSON.stringify(data));
})

Also, my personal preference is to use res.json as it sets the header automatically.

app.get('/search', function (req, res) {
  res.json(data);
})

EDIT:

The drawback to this approach is that the JSON file is only read once into memory. If you don't want the file read into memory or you're planning on modify the JSON on disk at some point then you should see Ian's Answer