const fs = require('fs');

fs.readFile('./test.txt', function(error, data) {
  if (!error) {
    data = data.toString(); 

    const firstLine = data.split('\n')[0];

    console.log(`${firstLine}`)
  }
});

Imagine that in file test.txt you have the following words:

Hello\nHi\nTest

I want to find word Hi and return that value in ${firstLine}.