Read file to base64

file-to-base64.js

const getBase64 = (img, callback) => {
  const reader = new FileReader();

  reader.addEventListener("load", () => callback(reader.result));
  reader.readAsDataURL(img);
};

const getFiles = event => {
  if (event.dataTransfer) {
    return event.dataTransfer.files;
  } else if (event.target) {
    return event.target.files;
  }
};

const handleImageFileChange = event => {
  event.preventDefault();

  const files = getFiles(event);

  getBase64(files[0], image => console.log(image));
};

const fileInputs = [].slice.call(
  document.querySelectorAll('input[type="file"]')
);

fileInputs.forEach(input => {
  input.addEventListener("change", event => handleImageFileChange(event));
});