Resize/crop/center in javascript through canvas to base64

app.js

var $uplImageBtn  = $('.pui--ev-upload'),
    $uplContainer = $('#uplProfileImg'),
    $previewImg   = $('.macc--s-pimg img');

    $uplImageBtn.click(function() {
      $uplContainer.trigger('click');
    });

    $uplContainer.on('change', function() {
      if (!this.files && !this.files[0]) {
        return;
      }

      var reader = new FileReader(),
          tmpImg = '';

      reader.onload = function (e) {
        $previewImg.attr('src', snapshotResize(e.target.result, 380, 285));
      }

      reader.readAsDataURL(this.files[0]);
    });

    function snapshotResize (srcData, width, height) {
      var imageObj = new Image(),
          canvas   = document.createElement("canvas"),
          ctx      = canvas.getContext('2d'),
          xStart   = 0,
          yStart   = 0,
          aspectRadio,
          newWidth,
          newHeight;

      imageObj.src  = srcData;
      canvas.width  = width;
      canvas.height = height;

      aspectRadio = imageObj.height / imageObj.width;

      if(imageObj.height < imageObj.width) {
         //horizontal
         aspectRadio = imageObj.width / imageObj.height;
         newHeight   = height,
         newWidth    = aspectRadio * height;
         xStart      = -(newWidth - width) / 2;
      } else {
         //vertical
         newWidth  = width,
         newHeight = aspectRadio * width;
         yStart    = -(newHeight - height) / 2;
      }

      ctx.drawImage(imageObj, xStart, yStart, newWidth, newHeight);

      return canvas.toDataURL("image/jpeg", 0.75);
    }