我不明白一件事:
var comein = document.getElementById("comein");
var enter = new Expand({ elem : comein });
function Expand (options) {
this._elem = options.elem;
console.log(this._elem); // i have a div element
}
Expand.prototype = {
check : function () {
var comInClassName = this._elem.className; // i have an error: this._elem is undefined
if (comInClassName == "open"){
this.close();
}
if (comInClassName == "close"){
this.open();
}
}
}
log_in.addEventListener("click", enter.check, false);
如果在扩展中我有一个普通元素,为什么我在原型方法中有错误?谢谢