JS代码：

 <script>
	var forEach=function(t,o,r){if("[object Object]"===Object.prototype.toString.call(t))for(var c in t)Object.prototype.hasOwnProperty.call(t,c)&&o.call(r,t[c],c,t);else for(var e=0,l=t.length;l>e;e++)o.call(r,t[e],e,t)};

	var hamburgers = document.querySelectorAll(".hamburger");
	if (hamburgers.length > 0) {
	  forEach(hamburgers, function(hamburger) {
		hamburger.addEventListener("click", function() {
		  this.classList.toggle("is-active");
		}, false);
	  });
	}
  </script>