下面这个降频函数 debounce 能让你的代码变的高效：
<code class="language-javascript">// 返回一个函数，that, as long as it continues to be invoked, will not
// be triggered. The function will be called after it stops being called for
// N milliseconds. If `immediate` is passed, trigger the function on the
// leading edge, instead of the trailing.
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);
};
};
// Usage
var myEfficientFn = debounce(function() {
// All the taxing stuff you do
}, 250);
window.addEventListener('resize', myEfficientFn);</code>debounce 函数在给定的时间间隔内只允许你提供的回调函数执行一次，以此降低它的执行频率。当遇到高频触发的事件时，这样的限制显得尤为重要。
