throttle function

gistfile1.js

function throttle (fn, timeout) {
  var ctx, args, wait = false

  return function () {
    if (wait) {
      ctx = this
      args = arguments
      return
    }
    wait = true
    fn.apply(this, arguments)
    setTimeout(function () {
      wait = false
      var _ctx = ctx
      var _args = args
      ctx = null
      args = null
      _args && fn.apply(_ctx, _args)
    }, timeout)
  }
}