function throttle(func, delay) {

  var last, deferTimer

  return function() {

    var _this = this

    var _args = arguments

    var now = +new Date()

    if(last && now < last + delay) {

      clearTimeout(deferTimer)

      deferTimer = setTimeout(function() {

        last = now

        func.apply(_this, _args)

      }, delay)

    }else {

      last = now

      func.apply(_this, _args)

    }

  }

}

​

function ajax(value) {

  console.log('ajax request ' + value)

}

​

var throttleAjax = throttle(ajax, 1000)

​

var input = document.getElementById('search')

input.addEventListener('keyup', function(e) {

  throttleAjax(e.target.value)

})