throttle.js

スクロールなどのイベントを任意の時間の間隔で実行します。

/**
 * @desc - 関数などのイベントを任意の時間が経つたびに実行します。
 * @link - http://scn.sap.com/community/labs/blog/2014/04/30/debounce-and-throttle-in-javascript
 * @example
 * $(window).on('scroll', throttle(function() {
 * func();
 * }, 300));
 */
function throttle(func, wait, options) {
  var context, args, result;
  var timeout = null;
  var previous = 0;
  options || (options = {});

  var later = function() {
    previous = options.leading === false ? 0 : _.now();
    timeout = null;
    result = func.apply(context, args);
    context = args = null;
  };

  return function() {
    var now = _.now();
    if (!previous && options.leading === false) previous = now;

    var remaining = wait - (now - previous);
    context = this;
    args = arguments;
    if (remaining <= 0) {
      clearTimeout(timeout);
      timeout = null;
      previous = now;
      result = func.apply(context, args);
      context = args = null;
    } else if (!timeout && options.trailing !== false) {
      timeout = setTimeout(later, remaining);
    }
    return result;
  };
};