我在IE11中引发了一个javascript错误,该错误禁止在页面上滚动鼠标。我想知道代码的问题是什么,以及是否可以轻松修改它以修复它。
错误是: {exception}无法获取未定义或空引用的属性“长度”
它出现在这个代码块中,在第8行中,如图所示,处理程序是一个空引用:
return {
add: function(elem, event, handler) {
if(!elem.events) {
elem.events = {};
elem.handle = function(e) {
var ret, handlers = elem.events[e.type];
e = fixEvent(e);
for(var i = 0, len = handlers.length; i < len; i++) {
if(handlers[i]) {
ret = handlers[i].call(elem, e);
if(ret === false) {
e.preventDefault();
e.stopPropagaton();
}
}
}
};
}
if(!elem.events[event]) {
elem.events[event] = [];
if(elem.addEventListener) elem.addEventListener(event, elem.handle, false);
else if(elem.attachEvent) elem.attachEvent('on'+event, elem.handle);
}
elem.events[event].push(handler);
},
remove: function(elem, event, handler) {
var handlers = elem.events[event];
for(var i = handlers.length - 1; i >= 0; i--) {
if(handlers[i] === handler) {
handlers.splice(i,1);
}
}
if(!handlers.length) {
delete elem.events[event];
if(elem.removeEventListener) elem.removeEventListener(event, elem.handle, false);
else if(elem.detachEvent) elem.detachEvent('on'+event, elem.handle);
}
}
};