debounce.js

function debounce(fun, wait = 0) {
  let id = null;
  return () => {
    if (id !== null) clearTimeout(id)
    id = setTimeout(() => {
      fun();
      id = null;
    }, wait);
  };
}

debounce.ts

const debounce = (fun: () => any, wait = 0): () => void => {
  let id: NodeJS.Timer|null = null;
  return () => {
    if (id !== null) clearTimeout(id)
    id = setTimeout((): void => {
      fun()
      id = null
    }, wait)
  }
}

promised_debounce.js

function debounce(fun, wait = 0) {
  let id = null;
  return (x) => {
    return new Promise(resolve => {
      if (id !== null) clearTimeout(id);
      id = setTimeout(() => {
        id = null;
        resolve(fun(x));
      }, wait);
    });
  }
}

// var hoge = debounce(x=>x + 1, 1000)

// hoge(1).then(x => console.log(x));
// hoge(3).then(x => console.log(x));
// hoge(2).then(x => console.log(x));
// hoge(5).then(x => console.log(x));