Code to read the file uploaded to a page (using FileReader object)

example.js

// file input
var input = document.getElementById('fileinput');

// treatment when file is selected
var handleFiles = function () {

  // log the size of the file
  console.log('Size of the file is ' + this.files[0].size/1000 + ' kB');

  // instantiate a new FileReader object
  var fr = new FileReader();

  // loading files from the file system is an asynchronous
  // operation, run this function when the loading process
  // is complete
  fr.addEventListener('loadend', function() {
    // send the file over web sockets
    // ws.send(fr.result);
    console.log('end of loading');
  });

  // load the file into an array buffer
  fr.readAsArrayBuffer(this.files[0]);

};

// applying treatment to input
input.addEventListener('change', handleFiles, false);