Question

/**
 * @param { function } func 函数
 * @param { number } wait 延迟执行毫秒数
 * @param { number } type 1 表时间戳版，2 表定时器版
 */
export function throttle(func, wait ,type) {
  let previous, timeout;
  if(type===1){
    previous = 0;
  }else if(type===2){
    timeout = null;
  }
  return function() {
    let context = this;
    let args = arguments;
    if(type===1){
      let now = Date.now();

      if (now - previous > wait) {
        func.apply(context, args);
        previous = now;
      }
    }else if(type===2){
      if (!timeout) {
        timeout = setTimeout(() => {
          timeout = null;
          func.apply(context, args)
        }, wait)
      }
    }

  }
}