如何通过JavaScript加载本地图片并转换成Base64 (我不想加载到浏览器中)

// HTML
<input type="file" id="fileInput">

// JavaScript
document.getElementById('fileInput').addEventListener('change', function(event) {
  var file = event.target.files[0];
  var reader = new FileReader();

  reader.onload = function(event) {
    var dataURL = event.target.result;
    var image = new Image();

    image.onload = function() {
      var canvas = document.createElement('canvas');
      var context = canvas.getContext('2d');

      canvas.width = image.width;
      canvas.height = image.height;
      context.drawImage(image, 0, 0);

      var base64 = canvas.toDataURL('image/png');
      console.log(base64);
    };

    image.src = dataURL;
  };

  reader.readAsDataURL(file);
});