Uploading a zip file using POST in Javascript fails silently

Question

I am working on a web application (using JQuery version 2.2.4) that allows users to submit images and data to our server. When users decide to upload their submissions, my code should generate a zip file using the JSZip library and upload it to our server using POST. After some searching here on StackExchange, I came up with this code:

var zip = new JSZip();   // Create the object representing the zip file

// ...Add the data and images

console.log('Generating compressed archive...');
zip.generateAsync({
    compression: 'DEFLATE',
    type: 'blob'
}).then(function(zc) {// Function called when the generation is complete
    console.log('Compression complete!');
    // Create file object to upload
    var fileObj = new File([zc], fileName);
    console.log('File object created:', fileObj);
    $.post('http://myurl/submit', {
    data: fileObj,
    }).done(function() {
        console.log('Ajax post successful.');
    })
    .fail(function(jqXHR, textStatus, errorThrown) {
        console.log('Ajax post failed. Status:', textStatus);
        console.log(errorThrown);
    });
});

My code prints the File object created message, the file object itself looks OK, but then I get nothing else. A silent failure. The POST call does not even appear in the Net panel for Firebug.

After more searching, I also tried to add this code beforehand:

$(document).ajaxError(function(event, jqxhr, settings, thrownError) {
    console.log('Ajax post failed. Event:', event);
    console.log('Ajax settings:', settings);
    console.log(thrownError);
});

But that doesn't get triggered. There's clearly some error I am making in setting up the callbacks for errors - what could I try?

Answer 1

I have managed to get the upload to work creating a FormData object and sticking my file into it. Here is the code:

var zip = new JSZip();   // Create the object representing the zip file

// ...Add the data and images

console.log('Generating compressed archive...');
zip.generateAsync({
    compression: 'DEFLATE',
    type: 'blob'
}).then(function(zc) {// Function called when the generation is complete
    console.log('Compression complete!');
    // Create file object to upload
    var fileObj = new File([zc], fileName);
    console.log('File object created:', fileObj);
    var fd = new FormData();
    fd.append('fileName', fileName);
    fd.append('file', fileObj);
    fd.append('mimeType', 'application/zip');
    // POST Ajax call
    $.ajax({
        type: 'POST',
        url: 'http://myurl/submit',
        data: fd,
        contentType: false,
        processData: false,
    }).done(function() {
        console.log('Ajax post successful.');
    }).fail(function(jqXHR, textStatus, errorThrown) {
        console.log('Ajax post failed. Status:', textStatus);
        console.log(jqXHR);
        console.log(errorThrown);
    });
});

This was inspired by the other StackExchange answers linked to by David Duponchel.