js base64图片下载

download(base64) {
                let imgData = base64;//这里放需要下载的base64
                this.downloadFile('海报.png', imgData);
            },
            downloadFile(fileName, content) {
                let aLink = document.createElement('a');
                let blob = this.base64ToBlob(content); //new Blob([content]);
         
                let evt = document.createEvent("HTMLEvents");
                evt.initEvent("click", true, true);//initEvent 不加后两个参数在FF下会报错  事件类型，是否冒泡，是否阻止浏览器的默认行为
                aLink.download = fileName;
                aLink.href = URL.createObjectURL(blob);
         
                // aLink.dispatchEvent(evt);
                aLink.click()
            },
              //base64转blob
              base64ToBlob(code) {
                let parts = code.split(';base64,');
                let contentType = parts[0].split(':')[1];
                let raw = window.atob(parts[1]);
                let rawLength = raw.length;
         
                let uInt8Array = new Uint8Array(rawLength);
         
                for (let i = 0; i < rawLength; ++i) {
                  uInt8Array[i] = raw.charCodeAt(i);
                }
                return new Blob([uInt8Array], {type: contentType});
            },