button onclick event handler

Discussion in 'ASP .Net' started by moondaddy, Aug 25, 2006.

  1. moondaddy

    moondaddy Guest

    I have an asp.net 2.0 application and put a html button on a web page. I
    double clicked on the button and it crated the event handler for me and
    created the stub js function for it like this:

    <input id="btnQryFunctions" type="button" value="Query Functions"
    language="javascript" onclick="return btnQryFunctions_onclick()" />

    and the function it created was:

    function btnQryFunctions_onclick() {

    }

    Question: why did it create this code? onclick="return
    btnQryFunctions_onclick()"

    Normally I would have just written: onclick="btnQryFunctions_onclick()" with
    out the 'return'. What does the word 'return' do for me in this case?

    Thanks.


    --
    ail
     
    moondaddy, Aug 25, 2006
    #1
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  2. Hi,

    In this case, it indicates that the function 'btnQryFunctions_onclick()'
    will return a boolean value based on which the form will be submitted back.

    For example, you might have some validation script within
    'btnQryFunctions_onclick()' script function that. In case the validation
    fails and you do not want the form to be submitted, you can return false
    which will not let the form to be submitted.

    Regards,
    Augustin
    http://augustinprasanna.blogspot.com

    "moondaddy" wrote:

    > I have an asp.net 2.0 application and put a html button on a web page. I
    > double clicked on the button and it crated the event handler for me and
    > created the stub js function for it like this:
    >
    > <input id="btnQryFunctions" type="button" value="Query Functions"
    > language="javascript" onclick="return btnQryFunctions_onclick()" />
    >
    > and the function it created was:
    >
    > function btnQryFunctions_onclick() {
    >
    > }
    >
    > Question: why did it create this code? onclick="return
    > btnQryFunctions_onclick()"
    >
    > Normally I would have just written: onclick="btnQryFunctions_onclick()" with
    > out the 'return'. What does the word 'return' do for me in this case?
    >
    > Thanks.
    >
    >
    > --
    > ail
    >
    >
    >
     
    =?Utf-8?B?QXVndXN0aW4gUHJhc2FubmE=?=, Aug 25, 2006
    #2
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  3. Hello Moondaddy,

    I think difference here is the button you added is a html submit button
    rather than ASP.NET server button. so the "" event handler you see here is
    a client-side script rather than server-side event handler.

    ===========
    <script language="javascript" type="text/javascript">
    // <!CDATA[

    function Submit1_onclick() {

    }

    // ]]>
    </script>
    ====================

    And in client-side script event hander, we can stop the event by return
    false in event handler, that's why the auto-generated "onclick" attribute
    is like below:

    onclick="return function_hander();"





    If you add a ASP.NET server button and double click it, it will add an
    server-side event handler in code-behind. and this code is executed at
    server-side after postback and haven't return type.

    Hope this help clarify this. If you have anything unclear, please feel free
    to post here.



    Sincerely,

    Steven Cheng

    Microsoft MSDN Online Support Lead



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    This posting is provided "AS IS" with no warranties, and confers no rights.
     
    Steven Cheng[MSFT], Aug 25, 2006
    #3
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