GIF Frame Disposal Correction Algorithm

gifFrameDisposal.js

function explodeGif(gifUrl) {
    return gifler(gifUrl)._animatorPromise.then(function(gif) {

        let current = createTempCanvas(gif.width, gif.height, 'current');
        let currentCtx = current.getContext('2d');
        let temp = createTempCanvas(gif.width, gif.height, 'temp');
        let tempCtx = temp.getContext('2d');

        gif._animationLength = 0;
        for (let i = 0; i < gif._frames.length; i++) {
            let cFrame = gif._frames[i]; // current frame
            gif._animationLength += cFrame.delay;

            switch (cFrame.disposal) { // how to recover AFTER drawing the frame
                case 2: // dispose to background (fill frame rect with transparency)
                    tempCtx.putImageData(new ImageData(cFrame.pixels, gif.width, gif.height), 0, 0);
                    currentCtx.drawImage(temp, cFrame.x, cFrame.y, cFrame.width, cFrame.height, cFrame.x, cFrame.y, cFrame.width, cFrame.height);
                    gif._frames[i].data = currentCtx.getImageData(0, 0, gif.width, gif.height);
                    currentCtx.clearRect(cFrame.x, cFrame.y, cFrame.width, cFrame.height);
                    break;
                case 3: // dispose to previous (restore frame rect)
                    tempCtx.putImageData(new ImageData(cFrame.pixels, gif.width, gif.height), 0, 0);
                    let prev = currentCtx.getImageData(cFrame.x, cFrame.y, cFrame.width, cFrame.height);
                    currentCtx.drawImage(temp, cFrame.x, cFrame.y, cFrame.width, cFrame.height, cFrame.x, cFrame.y, cFrame.width, cFrame.height);
                    gif._frames[i].data = currentCtx.getImageData(0, 0, gif.width, gif.height);
                    currentCtx.putImageData(prev, cFrame.x, cFrame.y);
                    break;
                default: // do not dispose (none or unspecified)
                    tempCtx.putImageData(new ImageData(cFrame.pixels, gif.width, gif.height), 0, 0);
                    currentCtx.drawImage(temp, cFrame.x, cFrame.y, cFrame.width, cFrame.height, cFrame.x, cFrame.y, cFrame.width, cFrame.height);
                    gif._frames[i].data = currentCtx.getImageData(0, 0, gif.width, gif.height);
                    break;
            }
        }
        return gif;
    });
}

This snipped explodes a GIF (splits into frames) and prepares it to be rendered on a canvas element, which includes fixing the frame disposal. The lib Gifler or any other of your choice is required.
http://themadcreator.github.io/gifler/assets/gifler.js