filestash/client/utilities/backpressure.js

export function debounce(func, wait, immediate) {
	var timeout;
	return function() {
		var context = this, args = arguments;
		var later = function() {
			timeout = null;
			if (!immediate) func.apply(context, args);
		};
		var callNow = immediate && !timeout;
		clearTimeout(timeout);
		timeout = setTimeout(later, wait);
		if (callNow) func.apply(context, args);
	};
};



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