55 lines
1.1 KiB
TypeScript
55 lines
1.1 KiB
TypeScript
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/**
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* Debounce a function.
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*
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* @example
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*
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* ```ts
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* const A = debounce(myFunction, 1000)
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* ```
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*
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* @public
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* @see source - https://gist.github.com/ca0v/73a31f57b397606c9813472f7493a940
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*/
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export function debounce<T extends unknown[], U>(
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callback: (...args: T) => PromiseLike<U> | U,
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wait: number
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) {
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let state:
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| undefined
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| {
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timeout: ReturnType<typeof setTimeout>
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promise: Promise<U>
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resolve: (value: U | PromiseLike<U>) => void
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reject: (value: any) => void
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latestArgs: T
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} = undefined
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const fn = (...args: T): Promise<U> => {
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if (!state) {
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state = {} as any
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state!.promise = new Promise((resolve, reject) => {
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state!.resolve = resolve
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state!.reject = reject
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})
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}
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clearTimeout(state!.timeout)
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state!.latestArgs = args
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state!.timeout = setTimeout(() => {
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const s = state!
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state = undefined
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try {
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s.resolve(callback(...s.latestArgs))
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} catch (e) {
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s.reject(e)
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}
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}, wait)
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return state!.promise
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}
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fn.cancel = () => {
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if (!state) return
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clearTimeout(state.timeout)
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}
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return fn
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}
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