illustrator script to convert the base64 into image

this code is not working to download any image from the adobe illustrator.

function base64(imgPath){
    const base64string = imgPath;
    const pageImage = new Image();
    pageImage.src='data:image/png;base64,' + base64string;
    pageImage.onload = function() {
        const canvas = document.createElement('canvas');
        canvas.width = pageImage.naturalWidth;
        canvas.height= pageImage.naturalHeight;
        const ctx = canvas.getContext('2d');
        ctx.imageSmoothingEnabled = false;
        ctx.drawImage(pageImage, 0, 0);
        saveScreenshot(canvas);
    }
}
function saveScreenshot(canvas) {
    let fileName = "image"
    const link = document.createElement('a');
    link.download = fileName + '.png';
    canvas.toBlob(function(blob) {
        link.href = URL.createObjectURL(blob);
        link.click();
    });
};