前端base64转Blob，Blob转文件下载

base64转Blob

 dataURLtoBlob = (dataurl) => {
   
        try {
   
            let arr = dataurl.split(',');
            let mime = arr[0].match(/:(.*?);/)[1];
            let bstr = atob(arr[1]);
            let n = bstr.length;
            let u8arr = new Uint8Array(n);

            while (n--) {
   
                u8arr[n] = bstr.charCodeAt(n);
            }
            return new Blob([u8arr], {
    type: mime });
        } catch{
   
            let arr = dataurl.split(',');
            // let mime = arr[0].match(/:(.*?);/)[1];
            let bstr = atob(arr[0]);
            let n = bstr.length;
            let u8arr = new Uint8Array(n);

            while (n--) {
   
                u8arr[n] = bstr.charCodeAt(n);
            }
            return new Blob([u8arr]);
        }
    }

Blob转文件下载

res.data.fileName：后端带来的文件名；
res.data.data base64串；

           var eleLink = document.createElement("a");
            eleLink.download = res.data.fileName;
            eleLink.style.display = "none";
            // 字符内容转变成blob地址
            var blob = new Blob([this.dataURLtoBlob(res.data.data)]);
            eleLink.href = URL.createObjectURL(blob);
            // 触发点击
            document.body.appendChild(eleLink);
            eleLink.click();
            // 然后移除
            document.body.removeChild(eleLink);