Debounce utility

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import { describe, it, expect, vi } from 'vitest'
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import { debounce } from './debounce'
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describe('debounce', () => {
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  it('delays the callback', () => {
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    vi.useFakeTimers()
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    const fn = vi.fn()
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    const debounced = debounce(fn, 100)
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    debounced()
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    expect(fn).not.toHaveBeenCalled()
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    vi.advanceTimersByTime(100)
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    expect(fn).toHaveBeenCalledOnce()
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    vi.useRealTimers()
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  })
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})

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export function debounce<T extends (...args: unknown[]) => void>(
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  fn: T,
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  ms: number,
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): (...args: Parameters<T>) => void {
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  let timer: ReturnType<typeof setTimeout>
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  return (...args) => {
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    clearTimeout(timer)
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    timer = setTimeout(() => fn(...args), ms)
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  }
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}