214 lines
5.7 KiB
Markdown
214 lines
5.7 KiB
Markdown
# throttle-debounce
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[![Build Status][ci-img]][ci]
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[![BrowserStack Status][browserstack-img]][browserstack]
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[![Mentioned in Awesome Micro npm Packages][awesome-img]][awesome]
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Throttle and debounce functions.
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This module is the same as [jquery-throttle-debounce][jquery-throttle-debounce]
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([with some differences](#differences-with-original-module)), but it’s
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transferred to ES Modules and CommonJS format.
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## Install
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```sh
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npm install throttle-debounce --save
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```
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## Usage
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### `throttle`
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```js
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import { throttle } from 'throttle-debounce';
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const throttleFunc = throttle(1000, false, (num) => {
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console.log('num:', num);
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});
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// Can also be used like this, because noTrailing is false by default
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const throttleFunc = throttle(1000, (num) => {
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console.log('num:', num);
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});
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throttleFunc(1); // Will execute the callback
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throttleFunc(2); // Won’t execute callback
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throttleFunc(3); // Won’t execute callback
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// Will execute the callback, because noTrailing is false,
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// but if we set noTrailing to true, this callback won’t be executed
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throttleFunc(4);
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setTimeout(() => {
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throttleFunc(10); // Will execute the callback
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}, 1200);
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// Output
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// num: 1
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// num: 4
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// num: 10
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```
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### `debounce`
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```js
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import { debounce } from 'throttle-debounce';
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const debounceFunc = debounce(1000, false, (num) => {
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console.log('num:', num);
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});
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// Can also be used like this, because atBegin is false by default
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const debounceFunc = debounce(1000, (num) => {
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console.log('num:', num);
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});
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// Won’t execute the callback, because atBegin is false,
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// but if we set atBegin to true, this callback will be executed.
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debounceFunc(1);
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debounceFunc(2); // Won’t execute callback
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debounceFunc(3); // Won’t execute callback
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// Will execute the callback,
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// but if we set atBegin to true, this callback won’t be executed.
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debounceFunc(4);
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setTimeout(() => {
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debounceFunc(10); // Will execute the callback
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}, 1200);
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// Output
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// num: 4
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// num: 10
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```
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### Cancelling
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Debounce and throttle can both be cancelled by calling the `cancel` function.
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```js
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const throttleFunc = throttle(300, () => {
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// Throttled function
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});
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throttleFunc.cancel();
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const debounceFunc = debounce(300, () => {
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// Debounced function
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});
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debounceFunc.cancel();
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```
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The logic that is being throttled or debounced will no longer be called.
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## API
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### throttle(delay, noTrailing, callback, debounceMode)
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Returns: `Function`
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Throttle execution of a function. Especially useful for rate limiting execution
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of handlers on events like resize and scroll.
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#### delay
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Type: `Number`
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A zero-or-greater delay in milliseconds. For event callbacks, values around 100
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or 250 (or even higher) are most useful.
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#### noTrailing
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Type: `Boolean`
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Optional, defaults to false. If noTrailing is true, callback will only execute
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every `delay` milliseconds while the throttled-function is being called. If
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noTrailing is false or unspecified, callback will be executed one final time
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after the last throttled-function call. (After the throttled-function has not
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been called for `delay` milliseconds, the internal counter is reset)
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#### callback
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Type: `Function`
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A function to be executed after delay milliseconds. The `this` context and all
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arguments are passed through, as-is, to `callback` when the throttled-function
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is executed.
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#### debounceMode
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Type: `Boolean`
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If `debounceMode` is true (at begin), schedule `clear` to execute after `delay`
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ms. If `debounceMode` is false (at end), schedule `callback` to execute after
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`delay` ms.
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### debounce(delay, atBegin, callback)
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Returns: `Function`
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Debounce execution of a function. Debouncing, unlike throttling, guarantees that
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a function is only executed a single time, either at the very beginning of a
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series of calls, or at the very end.
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#### delay
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Type: `Number`
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A zero-or-greater delay in milliseconds. For event callbacks, values around 100
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or 250 (or even higher) are most useful.
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#### atBegin
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Type: `Boolean`
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Optional, defaults to false. If `atBegin` is false or unspecified, callback will
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only be executed `delay` milliseconds after the last debounced-function call. If
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`atBegin` is true, callback will be executed only at the first
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debounced-function call. (After the throttled-function has not been called for
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`delay` milliseconds, the internal counter is reset).
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#### callback
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Type: `Function`
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A function to be executed after delay milliseconds. The `this` context and all
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arguments are passed through, as-is, to `callback` when the debounced-function
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is executed.
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## Differences with original module
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- Dependancy on jQuery is removed, so if you rely on GUIDs set by jQuery, plan
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accordingly
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- There is no standalone version available, so don’t rely on `$.throttle` and
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`$.debounce` to be available
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## Browser support
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Tested in IE9+ and all modern browsers.
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## Test
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For automated tests, run `npm run test:automated` (append `:watch` for watcher
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support).
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## License
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<!-- prettier-ignore-start -->
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**Original module license:** Copyright (c) 2010 "Cowboy" Ben Alman (Dual licensed under the MIT and GPL licenses. http://benalman.com/about/license/)
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**This module license:** MIT © [Ivan Nikolić](http://ivannikolic.com)
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[ci]: https://travis-ci.org/niksy/throttle-debounce
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[ci-img]: https://travis-ci.org/niksy/throttle-debounce.svg?branch=master
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[browserstack]: https://www.browserstack.com/
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[browserstack-img]: https://www.browserstack.com/automate/badge.svg?badge_key=QWo5dGJqTzNkMWFnVXZqYzNvVDF1Q2p2Mm84Skc5ZTZFUUlnYkdEcFhQTT0tLTc1bVR3U284Uk9LZEFiSGR0NS8rY1E9PQ==--4a20321e30f225033ed6840c2fb71c6d1a8d2d1a
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[awesome]: https://github.com/parro-it/awesome-micro-npm-packages
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[awesome-img]: https://awesome.re/mentioned-badge.svg
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[jquery-throttle-debounce]: https://github.com/cowboy/jquery-throttle-debounce
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<!-- prettier-ignore-end -->
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