throttle AND debounce

throttle-AND-debounce.js

var throttle = function (fn,delay, immediate, debounce) {
  var curr = +new Date(),//当前事件
  last_call = 0,
  last_exec = 0,
  timer = null,
  diff, //时间差
  context,//上下文
  args,
  exec = function () {
    last_exec = curr;
    fn.apply(context, args);
  };
  return function () {
    curr= +new Date();
    context = this,
    args = arguments,
    diff = curr - (debounce ? last_call : last_exec) - delay;
    clearTimeout(timer);
    if (debounce) {
      if (immediate) {
        timer = setTimeout(exec, delay);
      } else if (diff >= 0) {
        exec();
      }
    } else {
      if (diff >= 0) {
        exec();
      } else if (immediate) {
        timer = setTimeout(exec, -diff);
      }
    }
    last_call = curr;
  }
};


var debounce = function (fn, delay, immediate) {
  return throttle(fn, delay, immediate, true);
};