js实战之:下载base64编码的图片

js如何实现base64编码的图片数据下载功能？

创建image对象，加载完成触发下载事件

 var image = new Image();
image.src = base64str;	//指向图片地址，即base64字符串
//定义图片加载事件
image.onload = function() {
            var canvas = convertImageToCanvas(image);
            url = canvas.toDataURL("image/jpeg");
            var a = document.createElement('a');
            var event = new MouseEvent('click');
            a.download = (new Date()).getTime() + ".jpg"; // 指定下载图片的名称
            a.href = url;
            a.dispatchEvent(event); // 触发超链接的点击事件
 }

根据图片生成画布canvas

function convertImageToCanvas(image) {
        var canvas = document.createElement("canvas");
        canvas.width = image.width;
        canvas.height = image.height;
        canvas.getContext("2d").drawImage(image, 0, 0);
        return canvas;
}