Node.js gets the content of the txt file line by line

Paste the code directly:　　

const readline = require('readline') 
//Readline is a packaged module that implements standard input and output in Node.js. Through this module, we can read the data stream line by line. Modules can be referenced using require("readline"). 
const r1 = readline.createInterface({ 
  input: fs.createReadStream("data.txt") 
});

var i = 1; //Number of lines in txt 
r1.on('line', function(line){ //Event listener 
    console.log('Line from file:' + i + ":" + line); 
　　if (i == 1){ 
　　　　console.log(line) 
　　} 
　　i+=1; 
}) 
This operation is performed asynchronously,