Example of converting a file to a dataURL in ES6

toDataUrl.js

const toDataURL = url => fetch(url)
    .then(response => response.blob())
    .then(blob => new Promise((resolve, reject) => {
      const reader = new FileReader()
      reader.onloadend = () => resolve(reader.result)
      reader.onerror = reject
      reader.readAsDataURL(blob)
    }))

fetch has not so good support and is experimental

line 8, I think you make a typo.
change to like this

  }));

@rohmanhm yes!!!

awesome!

@rohmanhm I have updated the gist. Totally missed that 😳