jQuery ajaxSend Event

What Is ajaxSend?

ajaxSend is a global AjaxEvent (since jQuery 1.0; .on() binding since 1.7). jQuery triggers it on document just before any qualifying Ajax request is sent. All registered handlers run.

$(document).on("ajaxSend", function (event, jqXHR, ajaxOptions) {
  // runs just before every qualifying Ajax request is sent
});

// Order (per request):
// ajaxStart → ajaxSend → (response) → ajaxSuccess|ajaxError → ajaxComplete

// Opt out for one call:
$.ajax({ url: "/x", global: false });

How to Use ajaxSend

Bind once on document, then any jQuery Ajax call can notify that handler before it leaves.

1. Attach the handler to document with .on("ajaxSend", handler).
2. Make requests with $.ajax(), $.get(), $.post(), or .load().
3. Optionally filter with ajaxOptions.url (or other settings).
4. Use global: false on requests that must stay silent.
5. Prefer beforeSend when logic belongs to one call only.

Pseudocode

bind ajaxSend on document with handler(event, jqXHR, ajaxOptions)

when a jQuery Ajax request is about to be sent:
    if request.global === false:
        do not fire ajaxSend
        return

    if this is the first active global request:
        fire ajaxStart

    fire ajaxSend
        for each registered handler:
            call handler(event, jqXHR, ajaxOptions)

    send the HTTP request
    // response is not available yet — use ajaxComplete later

Cheat Sheet

Keep these facts handy while wiring global Ajax send hooks.

Live Preview

Run a real $.get() and watch the global ajaxSend handler update the log before the request leaves.

Ready — pick an action and click Run.

jQuery Examples

Short, copy-ready snippets. Open DevTools Console, or use Try It Yourself for a live editor.

$(document).on("ajaxSend", function () {
  $(".log").text("Triggered ajaxSend handler.");
});

$(".trigger").on("click", function () {
  $(".result").load("ajax/test.html");
});

Click .trigger → .load() starts
Before request leaves → .log shows
"Triggered ajaxSend handler."

$(document).on("ajaxSend", function (event, jqxhr, settings) {
  if (settings.url === "ajax/test.html") {
    $(".log").text("Triggered ajaxSend handler.");
  }
});

Matching URL → log shows handler message
Other URLs → handler runs, if-block skipped

$(document).on("ajaxSend", function (event, request, settings) {
  $("#msg").append(" Starting request at " + settings.url + " ");
});

Each outgoing request →
#msg gains " Starting request at URL "

Three parallel calls → three appends before responses

$(document).on("ajaxSend", function () {
  $("#log").append(" ajaxSend");
});

// Fires ajaxSend
$.get("/api/public");

// Does NOT fire ajaxSend
$.ajax({ url: "/api/silent", global: false });

Public $.get → ajaxSend runs
Private $.ajax({ global: false }) → silent
(per-request beforeSend still works)

var globalCount = 0;
var localCount = 0;

$(document).on("ajaxSend", function () {
  globalCount++;
});

$.ajax({
  url: "/a",
  beforeSend: function () { localCount++; }
});
$.ajax({
  url: "/b",
  beforeSend: function () { localCount++; }
});

// After both start sending:
// globalCount === 2, localCount === 2
// but each beforeSend only saw its own request

Two $.ajax() calls start
global ajaxSend count → 2
per-request beforeSend count → 2

Performance Notes

Global handlers are fine when they stay light. Filter by URL before touching the DOM, and prefer beforeSend for request-specific work.

Key Takeaways