Download binary data into the app sandbox using XHR2 request instead of cordova-file-transfer

Question

Cordova is \"sunsetting\" (going to deprecate) cordovan-plugin-file, see their blogpost.

No more work will be done on the file-transfer plugin by the Cord

Answer 1

With this code you can download big images as they are written by blocks of 1MB instead of doing the whole write at once. Without the 1MB writting I wasn't able to write files bigger than 4MB, but with this I've tested with files up to 40MB without problems

 window.resolveLocalFileSystemURL(cordova.file.externalDataDirectory, 
    function (dirEntry) {
        console.log('file system open: ' + dirEntry.name);
        createFile(dirEntry, "downloadedImage.jpg");
    }, onFSError);
    function onFSError(error) {
        alert(JSON.stringify(error));
    }
    function createFile(dirEntry, fileName) {
        // Creates a new file or returns the file if it already exists.
        dirEntry.getFile(fileName, {create: true, exclusive: false}, function(fileEntry) {

            var xhr = new XMLHttpRequest();
            xhr.open('GET', 'https://static.vix.com/es/sites/default/files/styles/large/public/imj/3/30-cosas-de-los-gatos-que-no-sabias-3.jpg', true);
            xhr.responseType = 'blob';

            xhr.onload = function() {
                if (this.status == 200) {
                    var blob = new Blob([this.response], { type: 'image/jpeg' });
                    writeFile(fileEntry, blob);
                }
            };
            xhr.send();
        }, onFSError);
    }

    function writeFile(fileEntry, data) {
       // Create a FileWriter object for our FileEntry (log.txt).
       fileEntry.createWriter(function (fileWriter) {

            fileWriter.onerror = function(e) {
                console.log("Failed file write: " + e.toString());
            };

            function writeFinish() {
                function success(file) {
                    alert("Wrote file with size: " + file.size);
                }
                function fail(error) {
                    alert("Unable to retrieve file properties: " + error.code);
                }
                fileEntry.file(success, fail);
            }
            var written = 0;
            var BLOCK_SIZE = 1*1024*1024; // write 1M every time of write
            function writeNext(cbFinish) {
                fileWriter.onwrite = function(evt) {
                    if (written < data.size)
                        writeNext(cbFinish);
                    else
                        cbFinish();
                };
                if (written) fileWriter.seek(fileWriter.length);
                fileWriter.write(data.slice(written, written + Math.min(BLOCK_SIZE, data.size - written)));
                written += Math.min(BLOCK_SIZE, data.size - written);
            }
            writeNext(writeFinish);
        });
    }