Since the article [JavaScript] Customizing MessageBox was published, many netizens have written to ask how to call the ShowInfo method on the server side. I thought of a compromise method to achieve it during the weekend.
First of all, we should be able to clarify why we use Page.Write to output the custom JS method to the page and why IE cannot recognize it and an "XXX is not defined" error will appear. The reason is simple, because the script we output using Page.Write appears at the top of the page. When IE reads that it is a javascript function, it starts executing it. However, the js file we linked to is not read by IE at this time, so IE cannot recognize the method we defined in the js file. Then why is write alert possible? Because alert is a script function embedded in IE, IE will recognize it regardless of whether there is a page or not.
Once you find the problem, it will naturally be solved:
1. Embed our customized method into IE. ---> It seems a bit whimsical, haha
. 2. Wait until the page is loaded before triggering the event. --->Trigger event, yes.
How do you know if the page has finished loading?
1. Through the status of the document
2. Triggered by the event (windows.onload)
The first one seems to be less safe. Sometimes it still shows that it is transmitting data even though it has been completely loaded (FF is the most obvious situation), so it is safer to use events.
Define a simple method, mount it in windows.onload, and make a mark when executing
var loadComplete = false;
function LoadCompleted()
{
loadComplete= true;
}
window.attachEvent("onload",LoadCompleted);
Haha, in this way we only need to judge whether the page is loaded by judging loadComplete.
var mImgdir = "";
var mCaption = "caption";
var mMsg = "Message";
var mOkClick= null;
function ShowMessage(imgdir,caption,msg,OkClick)
{
if(loadComplete)
{
KMessageBox.ShowInfo(mImgdir,mCaption,mMsg,mOkClick);
}
}
In this way, when loadComplete is not false, we will not execute the KMessageBox.ShowInfo() method, but there will be no JS error prompt.
This alone is not enough, because the output script is only executed once by IE when outputting the page, but loadComplete=false at this time, so we need to regularly detect whether the page has been loaded. When it comes to timing, we just use setTimeout & setInterval. We need constant detection here, so we use the setInterval method. The final code is as follows:
var loadComplete = false;
var mImgdir = "";
var mCaption = "caption";
var mMsg = "Message";
var mOkClick= null;
var timerID;
function ShowMessage(imgdir,caption,msg,OkClick)
{
if(loadComplete)
{
KMessageBox.ShowInfo(mImgdir,mCaption,mMsg,mOkClick);
//Unload this event window.detachEvent("onload",function(){LoadCompleted;}); //Stop timing triggering
window.clearInterval(timerID);
}
}
function LoadCompleted() { loadComplete=true; }
window.attachEvent("onload",LoadCompleted);
//Set the timing detection mechanism
timerID = window.setInterval(ShowMessage,1);
Of course, the above code is only compatible with IE because it uses attachEvent and detachEvent. As for making it compatible with other browsers, please refer to [JavaScript] Customizing Title Display Method for the treatment method:
if(!document.attachEvent)//Not IE
{
document.attachEvent = function(){document.addEventListener(arguments[0].substr(2),arguments[1],arguments[2])}
}
if(!window.attachEvent)//Not IE
{
window.attachEvent = function(){window.addEventListener(arguments[0].substr(2),arguments[1],arguments[2])}
}
On the server side, as long as StringBuilder produces the above script and then Writes it, it is enough. The above just provides an idea. Of course, there are other ways. For example, I don’t use scheduled detection. I directly mount it in windows.onload and let the page automatically monitor and execute automatically. It’s not a bad idea either:), as the saying goes. All roads lead to Rome~~~~~
The above ideas come from yui, and yui implements a more beautiful custom MessageBox. Friends who are interested can study it together.
http://www.cnblogs.com/walkingboy/archive/2006/08/28/autorun_customerfunction.html