How we can read a file in Node JS?

var fs = require("fs");
var buf = new Buffer(1024);

console.log("open existing file");
fs.open('file.txt', 'r+', function(err, fd) {
   if (err) {
      return console.error(err);
   }
   console.log("File opened");
   console.log("read the file");
   
   fs.read(fd, buf, 0, buf.length, 0, function(err, bytes){
      if (err){
         console.log(err);
      }
      console.log(bytes + " bytes read");

      if(bytes > 0){
         console.log(buf.slice(0, bytes).toString());
      }
   });
});