您可以尝试在浏览器中读取数据，客户端使用readAsArrayBuffermore docs on mozilla website。
但我不确定你是否能够在纯JS中解析.xlsx的内容，下面是一个库的例子：http://oss.sheetjs.com/js-xlsx/是什么
XLSX / XLSM / XLSB / XLS / SpreadsheetML（Excel Spreadsheet）/ ODS解析器和编写器

openPDF(data, "DataSheet.pdf");//data is your bytearray intead of pdf try to ur file format

// ...

function openPDF(resData, fileName) {
    var ieEDGE = navigator.userAgent.match(/Edge/g);
    var ie = navigator.userAgent.match(/.NET/g); // IE 11+
    var oldIE = navigator.userAgent.match(/MSIE/g);

    var blob = new $window.Blob([resData], {
        type: 'application/pdf'
    });

    if (ie || oldIE || ieEDGE) {
        $window.navigator.msSaveBlob(blob, fileName);
    } else {

        var file = new Blob([resData], {
            type: 'application/pdf'
        });
        var fileURL = URL.createObjectURL(file);

        $window.open(fileURL);
    }
}