Convert Image to Base 64 WebDriver JS and Node style

convert-img-to-base64.js

// This runs in a browser,
// it's usable with WebDriver as an injected script
function convertImagetoBase64(selector) {
  const image = document.querySelector(selector);
  const canvas = document.createElement("canvas");
  const context = canvas.getContext("2d");
  const { width, height } = image;
  canvas.width = width;
  canvas.height = height;
  context.drawImage(image, 0, 0, width, height);
  const base64String = canvas.toDataURL();
  return base64String;
}

save-base64-as-file.js

// This runs in Node
const fs = require("fs");

function saveBase64URLAsFile(base64URL, filename) {
  return new Promise((resolve, reject) => {
    const base64Data = dataURL.replace(/^data:image\/png;base64,/, "");
    const binaryData = Buffer.from(base64Data, "base64").toString("binary");
    fs.writeFile(filename, binaryData, "binary", err => {
      if (err) {
        reject(err);
      } else {
        resolve();
      }
    });
  });
}