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MVC maintain scrolling position – [best alternative suggested]

There is no standard way of handling this, this was a Microsoft hack to support their post back model. They needed this because every control did a post back and the user would constantly be pushed back to the top of the page.

The recommendation for use with MVC is to do most of your post back to servers using AJAX. So that the page doesn’t have to rerender the the focus is not moved. jQuery makes AJAX really easy, and there is even default forms like

<% Ajax.BeginForm(...) %>

Which will take care of the AJAX side of things for you.


The way MaintainScrollPositionOnPostback works in Asp.Net
is that it has a pair of hidden fields: __SCROLLPOSITIONX and __SCROLLPOSITIONY

On a postback, it sets these,

function WebForm_GetScrollY() {
if (__nonMSDOMBrowser) {
    return window.pageYOffset;
}
else {
    if (document.documentElement && document.documentElement.scrollTop) {
        return document.documentElement.scrollTop;
    }
    else if (document.body) {
        return document.body.scrollTop;
    }
}
return 0;
}
function WebForm_SaveScrollPositionSubmit() {
    if (__nonMSDOMBrowser) {
        theForm.elements['__SCROLLPOSITIONY'].value = window.pageYOffset;
        theForm.elements['__SCROLLPOSITIONX'].value = window.pageXOffset;
    }
    else {
        theForm.__SCROLLPOSITIONX.value = WebForm_GetScrollX();
        theForm.__SCROLLPOSITIONY.value = WebForm_GetScrollY();
    }
    if ((typeof(this.oldSubmit) != "undefined") && (this.oldSubmit != null)) {
        return this.oldSubmit();
    }
    return true;
    }

and then it calls RestoreScrollPosition:

function WebForm_RestoreScrollPosition() {
    if (__nonMSDOMBrowser) {
        window.scrollTo(theForm.elements['__SCROLLPOSITIONX'].value, theForm.elements['__SCROLLPOSITIONY'].value);
    }
    else {
        window.scrollTo(theForm.__SCROLLPOSITIONX.value, theForm.__SCROLLPOSITIONY.value);
    }
    if ((typeof(theForm.oldOnLoad) != "undefined") && (theForm.oldOnLoad != null)) {
        return theForm.oldOnLoad();
    }
    return true;
}

But (as most people say), MVC should be avoiding postbacks .


For anyone who want to use something easy as replacement, try this:

@{
    var scrollPositionX = string.Empty;        
    if(IsPost) {
        scrollPositionX = Request.Form["ScrollPositionX"];
    }
}

<form action="" method="post">
    <input type="hidden" id="ScrollPositionX" name="ScrollPositionX" value="@scrollPositionX" />
    <input type="submit" id="Submit" name="Submit" value="Go" />
</form>

$("#Submit").click(function () {
    $("#ScrollPositionX").val($(document).scrollTop());
});

$("#ScrollPositionX").each(function () {
    var val = parseInt($(this).val(), 10);
    if (!isNaN(val))
        $(document).scrollTop(val);
});

What's your thoughts on this?

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