setTimeout定时器写的防抖动

 <input type="text" id='demo'/>
    <span id='show'></span>
    <br>
    <input type="text" id='demo2'/>
    <span id='show2'></span>
    <script>
        function debounce (func, delay) {
            var timer;
            return function () {
                var context = this, args = arguments;
                clearTimeout(timer);
                timer = setTimeout(function () {
                    func.apply(context, args);
                }, delay);
            }
        }
        function update (e) {
            show.innerText = this.value;
        }
        function update2 () {
            show2.innerText = this.value;
        }
        demo.oninput = debounce(update, 300);

        demo2.oninput = debounce(update2, 600);