uploading two pictures

HTML

<div>
    <input type="file" id="imageLoader1" name="imageLoader" />
    <br/>
    <input type="file" id="imageLoader2" name="imageLoader" />
    <br/>
    <canvas id="canvas" style="background:red;"></canvas>
</div>

JavaScript

var imageLoader1 = document.getElementById('imageLoader1');
var imageLoader2 = document.getElementById('imageLoader2');
imageLoader1.addEventListener('change', handleImage, false);
imageLoader2.addEventListener('change', handleImage, false);
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
let z = 0.4; // zoom

canvas.width = 1000;
canvas.height = 500;

function handleImage(e) {
  if (e.target == imageLoader1) {
    let img = new Image();
    img.src = URL.createObjectURL(e.target.files[0]);
    img.onload = function() {
      ctx.drawImage(img, 0, 0, img.width, img.height, 0, 0, img.width * z, img.height * z);
    }
  }

  if (e.target == imageLoader2) {
    let img = new Image();
    img.src = URL.createObjectURL(e.target.files[0]);
    img.onload = function() {
      ctx.drawImage(img, 0, 0, img.width, img.height, img.width * z, img.height * z, img.width * z, img.height * z);
    }
  }
}