window.addEventListener("onbeforeunload",function() {return "are you sure?"});
^ 这似乎完全不起作用...页面将会在没有显示确认框的情况下关闭...
我意识到...
window.onbeforeunload = function() {return "are you sure?"}
这样做可以运行,但我想要增加功能(例如向“onbeforeunload”函数添加许多事件侦听器),而不是完全重写函数!
function addEvent(evt,fn,useCapture){if(this.addEventListener){this.addEventListener(evt,fn,useCapture);return true;}else if(this.attachEvent){var r=this.attachEvent('on'+evt,fn);return r;}else this['on'+evt]=fn;}Object.prototype.addEvent=addEvent;
(将函数写成这样:object.addEvent(event,function,useCapture);)。 - Alexandre Khouryevent.returnValue
(文档)。 - somewindow.addEventListener("beforeunload",() => {return 'Stop')};
- Shayan