jQuery.fx.interval?jQuery.fx.interval (since jQuery 1.4.3) is a global Number: milliseconds between animation ticks on the legacy timer path. Default is 13. It is a static property — not $el.something().
jQuery.fx.interval // read → usually 13
jQuery.fx.interval = 50; // write (stop all animations first)
// Ignored when requestAnimationFrame is available
// Deprecated 3.0 · Removed 4.0| Need | Use |
|---|---|
| Disable all effects | jQuery.fx.off = true |
| Stop / jump animations | .stop() · .finish() |
| Per-animation timing | duration / easing on .animate() |
| Modern motion | CSS transitions · Web Animations · rAF |
jQuery.fx.intervalOnly relevant for legacy timer fallback. Always stop animations before changing the value.
$(":animated").stop(true, true).jQuery.fx.interval = 50.13 when done experimenting (again with no animations running).| Piece | Required? | Role |
|---|---|---|
| Type | — | Number (milliseconds) |
| Default | — | 13 |
| Scope | — | One global value for the whole page |
| Idle first | Yes (to apply) | No animation may be running when you change it |
// Read
current = jQuery.fx.interval // e.g. 13
// Write (official rule)
if any animation is running:
stop them all first
jQuery.fx.interval = newMs
// Runtime behavior
if browser supports requestAnimationFrame:
jQuery uses rAF — interval is ignored
else:
timer fires every jQuery.fx.interval ms
each tick advances active tweensKeep these facts handy when reading legacy jQuery animation code.
| Topic | Detail |
|---|---|
| Syntax | jQuery.fx.interval (read / write Number) |
| Since | jQuery 1.4.3 |
| Default | 13 ms |
| Deprecated | jQuery 3.0 |
| Removed | jQuery 4.0 |
| rAF | When supported → interval ignored |
| Change rule | Stop all animations first |
| Sibling | jQuery.fx.off — disable effects |
Read or set fx.interval, then run a short .animate(). On modern browsers with rAF, both rates may look the same.
Short, copy-ready snippets. Open DevTools, or use Try It Yourself for a live editor.
Inspect the global value before changing anything.
$("#read").on("click", function () {
$("#out").text(
"jQuery.fx.interval = " + jQuery.fx.interval + " ms" +
"\ntypeof: " + typeof jQuery.fx.interval
);
});13.Number (milliseconds).Official pattern: idle the fx pipeline, change the interval, then animate.
function stopAll() {
$(":animated").stop(true, true);
}
$("#slow").on("click", function () {
stopAll();
jQuery.fx.interval = 50;
$("#box").css({ marginLeft: 0 }).animate({ marginLeft: 200 }, 2000);
});
$("#default").on("click", function () {
stopAll();
jQuery.fx.interval = 13;
$("#box").css({ marginLeft: 0 }).animate({ marginLeft: 200 }, 2000);
});13 back for other demos.Assigning while an animation is running does not reconfigure the active timer.
$("#go").on("click", function () {
jQuery.fx.interval = 13;
$("#box").stop(true, true)
.css({ marginLeft: 0 })
.animate({ marginLeft: 200 }, 4000);
});
$("#change-mid").on("click", function () {
// Property updates — active tween keeps the old timer
jQuery.fx.interval = 50;
$("#status").text("Set to 50 mid-flight — no reconfigure yet.");
});
$("#apply").on("click", function () {
$(":animated").stop(true, true);
jQuery.fx.interval = 50;
$("#status").text("Stopped all, set 50 — next animate uses it (timer path).");
});requestAnimationFrameIf rAF exists, modern jQuery ignores fx.interval for smooth updates.
$("#check").on("click", function () {
var hasRAF = typeof window.requestAnimationFrame === "function";
var msg = hasRAF
? "rAF supported — jQuery.fx.interval is ignored for ticks"
: "No rAF — jQuery.fx.interval controls the timer tick rate";
$("#out").text(
msg + "\njQuery.fx.interval = " + jQuery.fx.interval
);
});requestAnimationFrame.fx.interval matter.jQuery.fx.off (Not Interval Tuning)For global control today, disable effects with fx.off. Do not ship new code that tunes fx.interval.
// Practical sibling global — still supported
$("#off").on("click", function () {
jQuery.fx.off = true;
$("#panel").hide().fadeIn(800); // snaps to end when fx.off is true
$("#status").text("fx.off = true — effects jump to final state.");
});
$("#on").on("click", function () {
jQuery.fx.off = false;
$("#panel").hide().fadeIn(800);
$("#status").text("fx.off = false — normal animated fade.");
});
// Avoid in new code:
// jQuery.fx.interval = 50; // deprecated 3.0, removed 4.0fadeIn call; behavior depends on the flag.Common mistakes when touching this legacy global.
With requestAnimationFrame, assigning 50 often does nothing to smoothness.
Stop all tweens first. Mid-flight assignment updates the property only.
You cannot set a different interval per element or per queue.
Reading or writing the property will fail after upgrade — migrate away.
Duration still comes from .animate(…, 2000). Interval only sets tick frequency on the timer path.
jQuery.fx.interval existed from jQuery 1.4.3 through 3.x. It is deprecated in 3.0 and removed in 4.0. On browsers with requestAnimationFrame, changing it has no effect.
Legacy timer tuning only. Modern jQuery prefers requestAnimationFrame. Do not depend on this property for new features.
Bottom line: Learn it to understand old codebases. Prefer duration/easing, CSS transitions, Web Animations, or jQuery.fx.off for real control.
| Approach | Cost | Best for |
|---|---|---|
| Lower interval (e.g. 5) | More timer wakeups | Legacy-only; usually worse on old CPUs |
| Higher interval (e.g. 50) | Fewer ticks | Choppier motion; rarely worth it today |
| rAF / CSS transitions | Browser-optimized | New UI motion |
Tuning fx.interval is not a modern performance strategy. Let the browser drive frames (rAF / CSS), or turn effects off with jQuery.fx.off.
jQuery.fx.off — not interval tuning.One line: jQuery.fx.interval was the legacy animation metronome — learn it for old code; do not build new features on it.
Turn all jQuery animations off globally — the practical sibling to fx.interval.
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