Prevent page from posting back from JavaScript

Question

Possible Duplicate:
prevent postback of HtmlButton in C#

Here's my JavaScript function:

<script type = "text/javascript">
    function CheckForEmptySearchBox(id) {
        var index = id.substring(id.length - 1);
        var boxContent = document.getElementById("contentMain__lvTSEntry__txtClientName_" + index).value;
        if (boxContent == "") {
            alert("Please enter search criteria");
            return false;
        }
    }
</script>

And the markup:

<asp:Button ID="_btnSearch" runat="server" OnClientClick = "return CheckForEmptySearchBox(this.id)" />

This code is working, i.e. when the texbox is empty, the message prompt the user to enter search criteria and the javascript prevents the page to postback. However, when the user enters text, there's no message prompt but the page still doesn't postback. What's wrong?

EDIT

if (boxContent == "") {
     alert("Please enter search criteria");
     return false;
   }
   else {
     return true;
   }

The page is still not posting back.

I think you need to return true if the box text is empty – NiK Sep 05 '12 at 17:53 — NiK, Sep 05 '12 at 17:53

score 2 · Answer 1 · answered Sep 05 '12 at 17:54

2

you need to return true from your function if you mean it to return true....

answered Sep 05 '12 at 17:54

AndreasKnudsen

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score 1 · Accepted Answer · answered Sep 05 '12 at 17:57

<script type = "text/javascript">
        function CheckForEmptySearchBox(id) {
            var index = id.substring(id.length - 1);
            var boxContent = document.getElementById("contentMain__lvTSEntry__txtClientName_" + index).value;
            if (boxContent == "") {
                alert("Please enter search criteria");
                return false;
            }
else{ return true;}
        }

you are asking for a return onclientclick function and not returning any value when textbox having value that`s why its stuck

  <asp:Button ID="_btnSearch" runat="server" OnClientClick = "return CheckForEmptySearchBox(this.id)" />

score 1 · Answer 3 · answered Sep 05 '12 at 17:57

You are forgetting to return true if the validation passes:

function CheckForEmptySearchBox(id) {
        var index = id.substring(id.length - 1);
        var boxContent = document.getElementById("contentMain__lvTSEntry__txtClientName_" + index).value;
        if (boxContent == "") {
            alert("Please enter search criteria");
            return false;
        }

     return true; //<--you forgot this
    }

Prevent page from posting back from JavaScript

EDIT

3 Answers3