I found on SO this codesnipet to achieve this. The only problem would be that you will run into CORS Problem. If you are the owner of the page which hosted the image you can configure up to avoid CORS.

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)
  }))


toDataURL('https://wallpaperaccess.com/full/3678503.png')
  .then(dataUrl => {
    console.log('RESULT:', dataUrl)
  })

And here the Link where i found the source: https://stackoverflow.com/a/20285053/14807111