# Debounce work with setTimeout2() and clearTimeout2()

> Use setTimeout2() to run a function once after the calls stop coming, replacing the previous timer with the same id, and cancel it with clearTimeout2().

Framework: total5
Product: Total.js 5 (total5@0.0.19)
Language: en
Content-SHA256: e0a20f3b90203a51ae4c6bbdfe81c1fc468b6bba946d9f8046b8b7ad35a02bac
Snapshot: c0700e321579725c5cf4f5ace1ad7d2866d1b4f93c24a63c0b41b6b7998e976c
Sources: total5-installed@total5@0.0.19
Review: not-recorded

`setTimeout2(id, callback, timeout)` is `setTimeout` with a name. When you call it again with the **same id** before the time is over, the previous timer is cancelled and replaced: the callback runs once, after the calls stop. It is the usual way to save, reload or recalculate only once when many events arrive together (a burst of changes, typing, a flood of messages).

`clearTimeout2(id)` cancels the timer of that id and returns `true` when there was one and `false` when there was not.

The full form is `setTimeout2(id, callback, timeout, limit, a, b, c, d, e)`: the values after `limit` are passed to the callback. **Do not use `limit`** in `total5` 0.0.19: the idea is to run the callback at once after `limit` replacements, but the counter never starts (it is `undefined` and becomes `NaN`), so the callback is only ever called when the time is over. The example calls it ten times with a limit of 3 and the callback did not run early.

```js controllers/timers.js
exports.install = function() {
	ROUTE('GET /burst/', burst);
};

async function burst($) {

	const log = [];

	// three calls with the same id: only the last one runs
	setTimeout2('save', () => log.push('first'), 100);
	setTimeout2('save', () => log.push('second'), 100);
	setTimeout2('save', () => log.push('third'), 100);

	// a timer that is cancelled before it runs
	setTimeout2('gone', () => log.push('gone'), 100);
	const cancelled = clearTimeout2('gone');
	const nothing = clearTimeout2('never-set');

	// the values after the limit reach the callback
	setTimeout2('args', (a, b) => log.push(a + b), 50, 0, 'x', 'y');

	// the limit option does not run the callback early
	let early = 0;
	for (let i = 0; i < 10; i++)
		setTimeout2('limited', () => early++, 1000, 3);
	const stopped = clearTimeout2('limited');

	await new Promise(resolve => setTimeout(resolve, 300));
	$.json({ log: log, cancelled: cancelled, nothing: nothing, early: early, stopped: stopped });
}
```