fast_debounce.ts

// this is lightly better than simple debounce as:
// 1. it kicks of a new search immediately
// 2. it waits for a server re
function debounceLoadOptions(searchUrl: string) {
  let running = false
  let runNext: [string, OptionsCallback] | null = null

  const run = (inputValue: string, callback: OptionsCallback, force: boolean) => {
    if (running && !force) {
      runNext = [inputValue, callback]
    } else {
      running = true
      request({
        url: searchUrl,
        query: {q: inputValue},
      }).then(([, response]) => {
        const {options} = response as { options: SearchOption[] }
        callback(options)
        if (runNext) {
          const [nextInputValue, nextCallback] = runNext
          runNext = null
          run(nextInputValue, nextCallback, true)
        } else {
          running = false
        }
      })
    }
  }

  return (inputValue: string, callback: OptionsCallback) => run(inputValue, callback, false)
}