js应用-base64转文件并下载

base64编码可由后端转化，前端进行post请求，这是代替流输出的一种办法。
这样可以用于Post输出并下载文件，Post可以传输多达2G的内容，所以不用担心文件大小的问题！
<html>
    <head>
        <title>js-base64转文件 demo</title>
    </head>
    <body>
        <input type="button" value="点击下载" id="btnDownload" />
    </body>
</html>
<script>
    let utils={        
        dataURLtoBlob: function(dataurl) { //将base64转换为blob
            let arr = dataurl.split(','),
                mime = arr[0].match(/:(.*?);/)[1],
                bstr = atob(arr[1]),
                n = bstr.length,
                u8arr = new Uint8Array(n);
                
            while (n--) {
                u8arr[n] = bstr.charCodeAt(n);
            }

            return new Blob([u8arr], { type: mime });
        },        
        blobToFile: function(theBlob, fileName){ //将blob转换为file
            theBlob.lastModifiedDate = new Date();
            theBlob.name = fileName;
            return theBlob;
        },
        downloadFile:function(url,name='test'){
            let a = document.createElement("a")
            a.setAttribute("href",url)
            a.setAttribute("download",name)
            a.setAttribute("target","_blank")

            let clickEvent = document.createEvent("MouseEvents");
            clickEvent.initEvent("click", true, true);  
            a.dispatchEvent(clickEvent);
        },
        downloadFileByBase64:function(base64,name){
            let myBlob = this.dataURLtoBlob(base64)
            let myUrl = URL.createObjectURL(myBlob)
            this.downloadFile(myUrl,name)
        }
    }

    document.getElementById("btnDownload").onclick=function(){
        let base64Data="data:application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;base64,UEsDBBQAAAAIAFSsjFQxSZgR8gAAANMCAAALAAAAX3JlbHMvLnJlbHOs0kFOwzAQBdCrWN43kxaEEKrbDZvuEOICxp4kVmKPZU8gnI0FR IKWEKCtiqhiy5t//l i/l8/1hvJz IF0zZUVByWdVSYDBkXWiVHLlZ3MrtZv2Ig aSyJ2LWZSRkJXsmOMdQDYdep0rihjKS0PJay7H1ELUptctwqqubyDtd8jDTrGzSqadXUrx9BbxnG5qGmfwnszoMfCJL44SpVmnFlnJaYBXSv0zUV VUingNGZ1SQxOjMGiXcRU5hM7zL8iS ahXGfQMc6Sri5JMmNm8vOg78ys6fp809/7AB5ZW80aDCX8x1QSPyI4WM3NlwADAFBLAwQUAAAACABUrIxUxL9OQEYBAACVBAAAEwAAAFtDb250ZW50X1R5cGVzXS54bWyslE1OwzAQha8SeYsSFxYIoaZdAFuoBBcw9qSxGv/IMynt2VhwJK7AJKVFoNIftSvLnvfe92xF Xz/GI4XrsnmkNAGX4rLYiAy8DoY66elaKnKb8R4NHxZRsCMpR5LURPFWylR1 AUFiGC50kVklPE2zSVUemZmoK8GgyupQ6ewFNOXYYYDe hUm1D2cOCj1fYBA2K7G4l7FilUDE2ViviuZx784eSfxMKdvYarG3ECxaITG5F9KN/CWvjE79EsgayiUr0qBzLpAl6kkJEyYZid8yWoqGqrAbOaB1bCugaGTB55EhIZOGn9U64DgmOp6 fqXMfj2yRgjv5yquYQ mLRmKtEphnSvwN4sl4jAmUwRqAXFP8yt5bhJYNnL1BH7oP/RbS7DWE2dmvz2vhlPWHFOjVKPvl8sxNNvmbIrL/yYy 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        utils.downloadFileByBase64(base64Data,'abc.xlsx');
    }

</script>
js应用-base64转文件并下载

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