当AutoPostBack =“True”时，DropDownList不会触发onb​​eforeunload

我使用这些页面中描述的技术实现了“未保存的更改”警告：

“未保存数据”保护的客户端/ JS框架？

http://kenbrowning.blogspot.com/2009/01/using-jquery-to-standardize.html

除了页面上的DropDownList之外，这很有效。 它执行AutoPostBack，我希望onbeforeunload可以触发，因为未保存的更改将丢失，但它无法正常工作。 它应该提高onbeforeunload事件吗？ 我可以以某种方式让它提升事件吗？

编辑： DropDownList位于UpdatePanel内部，这意味着它不会卸载页面，这就是为什么没有触发onb​​eforeunload的原因。 有没有办法以编程方式触发事件？ 或者我必须滚动自己的模仿确认对话框？

Edit2我现在有一个解决方案，它将对话框添加到UpdatePanel的异步回发中。 我编辑了原始脚本，添加了对setConfirmAsyncPostBack（）的调用，如我的解决方案中所述。

这是我的javascript：

/****Scripts to warn user of unsaved changes****/ //https://stackoverflow.com/questions/140460 //http://jonstjohn.com/node/23 //Activates the confirm message onbeforeunload. function setConfirmUnload(on) { setConfirmAsyncPostBack(); if (on) { removeCheckFromNoWarnClasses(); fixIEonBeforeUnload(); window.onbeforeunload = unloadMessage return; } window.onbeforeunload = null } function unloadMessage() { return 'You have unsaved changes.'; } //Moves javascript from href to onclick to prevent IE raising onbeforeunload unecessarily //http://kenbrowning.blogspot.com/2009/01/using-jquery-to-standardize.html function fixIEonBeforeUnload() { if (!$.browser.msie) return; $('a').filter(function() { return (/^javascript\:/i).test($(this).attr('href')); }).each(function() { var hrefscript = $(this).attr('href'); hrefscript = hrefscript.substr(11); $(this).data('hrefscript', hrefscript); }).click(function() { var hrefscript = $(this).data('hrefscript'); eval(hrefscript); return false; }).attr('href', '#'); } //Removes warnings from Save buttons, links, etc, that have been can be given "no-warn" or "no-warn-validate" css class //"no-warn-validate" inputs/links will only remove warning after successful validation //use the no-warn-validate class on buttons/links that cause validation. //use the no-warn class on controls that have CausesValidation=false (eg a "Save as Draft" button). function removeCheckFromNoWarnClasses() { $('.no-warn-validate').click(function() { if (Page_ClientValidate == null || Page_ClientValidate()) { setConfirmUnload(false); } }); $('.no-warn').click(function() { setConfirmUnload(false); }); } //Adds client side events to all input controls to switch on confirmation onbeforeunload function enableUnsavedChangesWarning() { $(':input').one('change', function() { window.onbeforeunload = function() { return 'You have unsaved changes.'; } }); removeCheckFromNoWarnClasses(); } 

在我的ASP.NET页面中，当用户进行更改时：

  if (changed) { ... //Confirm unload if there are unsaved changes. //NB we also have to call fixIEonBeforeUnload() to fix links, done in in page load to include links that are rendered during callbacks ScriptManager.RegisterStartupScript(Page, GetType(), "unsavedchanges", "setConfirmUnload(true);", true); } else ... 

Answer 1

另请参阅使用jQuery选择DropDownlist时如何防止AutoPostBack

 //http://msdn.microsoft.com/en-us/magazine/cc163413.aspx //https://stackoverflow.com/questions/2424327/prevent-asp-net-dopostback-from-jquery-submit-within-updatepanel //Adds an event handler to confirm unsaved changes when an asynchronous postback is initialised by an UpdatePanel function setConfirmAsyncPostBack() { if (typeof (Sys.WebForms) === "undefined" || typeof (Sys.WebForms.PageRequestManager) === "undefined") return; var prm = Sys.WebForms.PageRequestManager.getInstance(); prm.add_initializeRequest(confirmAsyncPostBack); } //An event handler for asynchronous postbacks that confirms unsaved changes, cancelling the postback if they are not confirmed //Adds the confirmation to elements that have a css class of "warn" function confirmAsyncPostBack(sender, args) { if (window.onbeforeunload != null && args.get_postBackElement().className == "warn" && !unloadConfirmed()) args.set_cancel(true); } //Displays a confirmation dialog that imitates the dialog displayed by onbeforeunload function unloadConfirmed() { var confirmed = confirm("Are you sure you want to navigate away from this page?\n\n" + unloadMessage() + "\n\nPress OK to continue or Cancel to stay on the current page."); if (confirmed) window.onbeforeunload = null; return confirmed; }