在Vue 中，将base64图片转为File文件类型

base64ToFile(urlData, fileName) {
        let arr = urlData.split(',');
        let mime = arr[0].match(/:(.*?);/)[1];
        let bytes = atob(arr[1]); // 解码base64
        let n = bytes.length
        let ia = new Uint8Array(n);
        while (n--) {
            ia[n] = bytes.charCodeAt(n);
        }
        return new File([ia], fileName, { type: mime });
    },