react-native-image-color-pick

script.js

const script = `
    <script>
      function get_average_rgb(img) {
        var context = document.createElement('canvas').getContext('2d');
        var src = img;
        img = new Image;
        img.setAttribute('crossOrigin', '');
        img.src =  "data:image/png;base64," + src;
        img.onload = function () {
          context.imageSmoothingEnabled = true;
          context.drawImage(img, 0, 0, 1, 1);
          const i = context.getImageData(0, 0, 1, 1).data;
          const rgba = "rgba(" + i[0] + ',' + i[1] + ',' + [2] + ")"
          console.log(rgba)
          const HEX = "#" + ((1 << 24) + (i[0] << 16) + (i[1] << 8) + i[2]).toString(16).slice(1);
          window.ReactNativeWebView.postMessage(HEX);
        }
      }
      get_average_rgb('${base64}')
    </script>
    `;