js手写——防抖

js手写打卡Day01

// 事件触发后等待n秒才执行，期间如果重新触发就重新计时
// 每次触发清除一个定时器，再设置定时器

// 尾执行
const debounce = (fn,delay) => {
  let timer = null;
  return function(...args) {
      clearTimeout(timer);
      timer = setTimeout(() => {
        fn.apply(this,args);
      },delay)
  }
}

/* const log = debounce(()=> console.log('hello world'),1000);
log();
log();
log();
 */
// 立即执行
// 在尾执行的基础上加一个首执行
const debounce2 = (fn, delay, immediate) => {
  let timer = null;
  if (immediate === false) {
    return function (...args) {
      clearTimeout(timer);
      timer = setTimeout(() => {
        fn.apply(this, args);
      }, delay);
    }
  } else {
    return function (...args) {
      if (!timer) {
        fn.apply(this, args);
      }
      clearTimeout(timer);
      timer = setTimeout(() => {
        timer = null;
      }, delay);
    }
  }
}

const log = debounce2(()=> console.log('hello world'),1000,false);
log();
log();
log();