JarCastingthrottle-debounce
Throttle and debounce functions.
This module is the same as jquery-throttle-debounce (with some differences), but it’s transferred to ES Modules and CommonJS format.
Install
npm install throttle-debounce --save
Usage
throttle
import { throttle } from 'throttle-debounce';
const throttleFunc = throttle(1000, false, (num) => {
console.log('num:', num);
});
// Can also be used like this, because noTrailing is false by default
const throttleFunc = throttle(1000, (num) => {
console.log('num:', num);
});
throttleFunc(1); // Will execute the callback
throttleFunc(2); // Won’t execute callback
throttleFunc(3); // Won’t execute callback
// Will execute the callback, because noTrailing is false,
// but if we set noTrailing to true, this callback won’t be executed
throttleFunc(4);
setTimeout(() => {
throttleFunc(10); // Will execute the callback
}, 1200);
// Output
// num: 1
// num: 4
// num: 10
debounce
import { debounce } from 'throttle-debounce';
const debounceFunc = debounce(1000, false, (num) => {
console.log('num:', num);
});
// Can also be used like this, because atBegin is false by default
const debounceFunc = debounce(1000, (num) => {
console.log('num:', num);
});
// Won’t execute the callback, because atBegin is false,
// but if we set atBegin to true, this callback will be executed.
debounceFunc(1);
debounceFunc(2); // Won’t execute callback
debounceFunc(3); // Won’t execute callback
// Will execute the callback,
// but if we set atBegin to true, this callback won’t be executed.
debounceFunc(4);
setTimeout(() => {
debounceFunc(10); // Will execute the callback
}, 1200);
// Output
// num: 4
// num: 10
Cancelling
Debounce and throttle can both be cancelled by calling the cancel function.
const throttleFunc = throttle(300, () => {
// Throttled function
});
throttleFunc.cancel();
const debounceFunc = debounce(300, () => {
// Debounced function
});
debounceFunc.cancel();
The logic that is being throttled or debounced will no longer be called.
API
throttle(delay, noTrailing, callback, debounceMode)
Returns: Function
Throttle execution of a function. Especially useful for rate limiting execution of handlers on events like resize and scroll.
delay
Type: Number
A zero-or-greater delay in milliseconds. For event callbacks, values around 100 or 250 (or even higher) are most useful.
noTrailing
Type: Boolean
Optional, defaults to false. If noTrailing is true, callback will only execute every delay milliseconds while the throttled-function is being called. If noTrailing is false or unspecified, callback will be executed one final time after the last throttled-function call. (After the throttled-function has not been called for delay milliseconds, the internal counter is reset)
callback
Type: Function
A function to be executed after delay milliseconds. The this context and all arguments are passed through, as-is, to callback when the throttled-function is executed.
debounceMode
Type: Boolean
If debounceMode is true (at begin), schedule clear to execute after delay ms. If debounceMode is false (at end), schedule callback to execute after delay ms.
debounce(delay, atBegin, callback)
Returns: Function
Debounce execution of a function. Debouncing, unlike throttling, guarantees that a function is only executed a single time, either at the very beginning of a series of calls, or at the very end.
delay
Type: Number
A zero-or-greater delay in milliseconds. For event callbacks, values around 100 or 250 (or even higher) are most useful.
atBegin
Type: Boolean
Optional, defaults to false. If atBegin is false or unspecified, callback will only be executed delay milliseconds after the last debounced-function call. If atBegin is true, callback will be executed only at the first debounced-function call. (After the throttled-function has not been called for delay milliseconds, the internal counter is reset).
callback
Type: Function
A function to be executed after delay milliseconds. The this context and all arguments are passed through, as-is, to callback when the debounced-function is executed.
Differences with original module
- Dependancy on jQuery is removed, so if you rely on GUIDs set by jQuery, plan accordingly
- There is no standalone version available, so don’t rely on
$.throttleand$.debounceto be available
Browser support
Tested in IE9+ and all modern browsers.
Test
For automated tests, run npm run test:automated (append :watch for watcher support).
License
Original module license: Copyright (c) 2010 "Cowboy" Ben Alman (Dual licensed under the MIT and GPL licenses. http://benalman.com/about/license/)
This module license: MIT © Ivan Nikolić