throttle 函数啦 *_*

throttle1.js

 /**
   * 版本1 
   * Throttles a call to a method based on the time between calls.
   * @param {Function} fn The function call to throttle.
   * @param {Object} [context] context fn to run
   * @param {Number} [ms] The number of milliseconds to throttle the method call.
   * Passing a -1 will disable the throttle. Defaults to 150.
   * @return {Function} Returns a wrapped function that calls fn throttled.
   * @member KISSY
   */
  function throttle(fn, ms, context) {
      ms = ms || 150;

      if (ms === -1) {
          return (function () {
              fn.apply(context || this, arguments);
          });
      }

      var last = +new Date();

      return (function () {
          var now = +new Date();
          if (now - last > ms) {
              last = now;
              fn.apply(context || this, arguments);
          }
      });
  }

  
  

throttle2.js

var now = require('../time/now');
/**
 */
function throttle(fn, delay){
    var context, timeout, result, args,
        cur, diff, prev = 0;
    function delayed(){
        prev = now();
        timeout = null;
        result = fn.apply(context, args);
    }
    function throttled(){
        context = this;
        args = arguments;
        cur = now();
        diff = delay - (cur - prev);
        if (diff <= 0) {
            clearTimeout(timeout);
            prev = cur;
            result = fn.apply(context, args);
        } else if (! timeout) {
            timeout = setTimeout(delayed, diff);
        }
        return result;
    }
    return throttled;
}

module.exports = throttle;