Wed. Jan 26th, 2022

Requirement: I have REST WebService which is used to download a file from the Oracle UCM Server. The file extension is .xlsx

Now, when I invoke the REST WebService passing value of the valid parameter(s), it returns me the response in which the Document Content is Base64Encoded.

Thus, in this post, I will show you the JavaScript function that will Decode and Download the Document Content which is Base64Encoded.

Solution: For the solution of the above requirement we will use the below JavaScript code.

define([], function() {
  'use strict';

  var PageModule = function PageModule() {};

  PageModule.prototype.downloadFile_XLSX = function(fileBytes) {
    var blob;
    blob = converBase64toBlob(fileBytes,
    var filename = "test.xlsx";
    if (navigator.msSaveBlob) {
      navigator.msSaveBlob(blob, filename);
    } else {
      var link = document.createElement("a");
      if ( !== undefined) {
        var url = URL.createObjectURL(blob);
        link.setAttribute("href", url);
        link.setAttribute("download", filename); = 'hidden';

  function converBase64toBlob(content, contentType) {
    contentType = contentType || '';
    var sliceSize = 512;
    var byteCharacters = window.atob(
    var byteArrays = [];
    for (var offset = 0; offset < byteCharacters.length; offset +=
      sliceSize) {
      var slice = byteCharacters.slice(offset, offset + sliceSize);
      var byteNumbers = new Array(slice.length);
      for (var i = 0; i < slice.length; i++) {
        byteNumbers[i] = slice.charCodeAt(i);
      var byteArray = new Uint8Array(byteNumbers);
    var blob = new Blob(byteArrays, {
      type: contentType
    return blob;

  return PageModule;

Hence, the solution to our requirement.

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Thanks & Regards,
Susanto Paul

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By Susanto Paul

Susanto is an Oracle ACE, a qualified MCA, MBA, and a highly-skilled Senior Oracle Specialist. He is an enthusiastic Blogger and YouTuber who helps learners to solve their complex problems more efficiently. He has 9+ years of experience in multiple technologies like AWS, Oracle ADF, Oracle APEX, Oracle JET, Oracle VBCS, Oracle IDCS, Oracle PL/SQL, Oracle Integration Cloud, Java, JDBC, Servlets, JSP, Spring, Hibernate, HTML5, CSS3, JavaScript, TypeScript, NodesJS, Angular, MySQL, Oracle WebLogic Server, JUnit, JMeter, Selenium Web Driver, etc. He is a certified: Oracle Certified Professional Java SE 6 Programmer, Oracle ADF 11g Certified Implementation Specialist, Oracle Cloud Platform Application Integration 2020 Certified Specialist, Oracle Cloud Infrastructure Foundations 2020 Certified Associate, and Oracle Cloud Infrastructure Developer 2020 Certified Associate

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