Been looking for some help changing a jQuery.ajax() request into vanilla XMLHttpRequest for WordPress, but not really finding what I want. Can anyone help me reformat the below into vanilla JavaScript XMLHttpRequest?

    data: {
        'action': 'work_hour_form_handler',
        'work_hours_start': document.getElementById('work-hours--start').value,
        'work_hours_end': document.getElementById('work-hours--end').value,
        'break-hours_start': document.getElementById('break-hours--start').value,
        'break-hours_duration': document.getElementById('break-hours--duration').value,
        'working_days': document.getElementById('working-days').value
    headers: {},
    method: 'post',
    url: fpm_ajax.ajax_url
}).done(function (data) {
    // If successful
}).fail(function (jqXHR, textStatus, errorThrown) {
    // If fail
    console.log(textStatus + ': ' + errorThrown);
  • heads up the url: fpm_ajax.ajax_url comes from wp_localize_script( 'feelya_pm_scripts', 'fpm_ajax', [ 'ajax_url' => admin_url( 'admin-ajax.php' ) ] ); Commented Jul 28, 2017 at 9:14

1 Answer 1


Here's my take on it, although a bit late, but I am working on converting all jQuery.ajax() calls to vanilla JavaScript, so why not.

    // alpha JS request // no jQuery
    // https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/send#Example_POST
    // https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Using_XMLHttpRequest
    var request = new XMLHttpRequest();

    request.open('POST', fpm_ajax.ajax_url, true);
    request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded;');
    request.onload = function () {
        if (this.status >= 200 && this.status < 400) {
            // If successful
        } else {
            // If fail
    request.onerror = function() {
        // Connection error
    request.send('action=work_hour_form_handler&work_hours_start=' + document.getElementById('work-hours--start').value + '&work_hours_end=' + document.getElementById('work-hours--end').value);

Note that by using console.log(this) you can see the actual response and any thrown errors. Also note I haven't included all your data, only the first two.

This code comes from a working solution from my WordPress plugin. I wrote about in more detail here: How to replace jQuery.ajax() with vanilla JavaScript in WordPress.


  • 1
    yes! dude nice, quick question though - does the onload function work in a similar way to .done() in a normal jQuery ajax request? Commented Apr 25, 2018 at 8:16
  • Yes, it does work similar. And onerror works similar to fail().
    – Ciprian
    Commented Apr 25, 2018 at 10:00
  • Can you help me out here? wordpress.stackexchange.com/q/359762/52859 Commented Feb 29, 2020 at 17:14
  • 1
    I tried but fetch api, but that did not worked, now this code works like a charm, now i do not have to include jQuery on frontend, I'm making requests without jQuery now. Commented Jun 24, 2021 at 17:42
  • True, no need for jQuery.
    – Ciprian
    Commented Jun 24, 2021 at 19:04

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