HTML5 Blob Read / Write File API

blob_read_write.js

/**
* Save or open HTML 5 Blob Object-URL
* @see https://stackoverflow.com/questions/22724070/prompt-file-download-with-xmlhttprequest
* @param blob Blob
* @param fileBName String
*/
function saveOrOpenBlob(blob, fileName) {
    window.requestFileSystem = window.requestFileSystem || window.webkitRequestFileSystem;
    window.requestFileSystem(window.TEMPORARY, 1024 * 1024, function (fs) {
        fs.root.getFile(fileName, { create: true }, function (fileEntry) {
            fileEntry.createWriter(function (fileWriter) {
                fileWriter.addEventListener("writeend", function () {
                    window.location = fileEntry.toURL();
                }, false);
                fileWriter.write(blob, "_blank");
            }, function () { });
        }, function () { });
    }, function () { });
}//saveOrOpenBlob

/**
* Get HTML5 Blob URL via XMLHttpRequest
* @see https://stackoverflow.com/questions/14952052/convert-blob-url-to-normal-url
* @param fileContents String JSON String
*/ 
function getBlob(fileContents) {
  var textFileAsBlob = new Blob([fileContents], { type: 'text/plain' });
  var blobUrl = URL.createObjectURL(textFileAsBlob);
  var xhr = new XMLHttpRequest;
  xhr.responseType = 'blob';
  xhr.onload = function() {
     var recoveredBlob = xhr.response;
     var reader = new FileReader;
     reader.onload = function() {
       var blobAsDataUrl = reader.result;
       window.location = blobAsDataUrl;
     };
     reader.readAsDataURL(recoveredBlob);
  };
  xhr.open('GET', blobUrl);
  xhr.send();
}//getBlob

/**
 * Save a text as file using HTML <a> temporary element and Blob
 * @see https://stackoverflow.com/questions/49988202/macos-webview-download-a-html5-blob-file
 * @param fileName String
 * @param fileContents String JSON String
 * @author Loreto Parisi
*/
var saveBlobAsFile = function(fileName,fileContents) {
    if(typeof(Blob)!='undefined') { // using Blob
        var textFileAsBlob = new Blob([fileContents], { type: 'text/plain' });
        var downloadLink = document.createElement("a");
        downloadLink.download = fileName;
        if (window.webkitURL != null) {
            downloadLink.href = window.webkitURL.createObjectURL(textFileAsBlob);
        }
        else {
            downloadLink.href = window.URL.createObjectURL(textFileAsBlob);
            downloadLink.onclick = document.body.removeChild(event.target);
            downloadLink.style.display = "none";
            document.body.appendChild(downloadLink);
        }
        downloadLink.click();
    } else {
        var pp = document.createElement('a');
        pp.setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(fileContents));
        pp.setAttribute('download', fileName);
        pp.onclick = document.body.removeChild(event.target);
        pp.click();
    }
}//saveBlobAsFile