<script type="text/javascript">
    ////////////////////////////////
    // prototype.js is required
    ////////////////////////////////
    
    var tbox = '<%= txtSearch.ClientID %>';
    var sbtn = '<%= btnSearch.ClientID %>';
    
    Event.observe(window, 'load', init, false);

    function init(){
        Event.observe(tbox, "keypress", function(e){checkEnter(e)});
    }
    
    function checkEnter(e){
        if (e.keyCode == 13){
            $(sbtn).click();
            Event.stop(e);
        }
    }
</script>

<script type="text/javascript">
    var tbox = '<%= txtSearch.ClientID %>';
    var sbtn = '<%= btnSearch.ClientID %>';
    
    Event.observe(window, 'load', init, false);

    function init(){
        Event.observe(tbox, "keypress", function(e){checkEnter(e)});
    }
    
    function checkEnter(e){
        if (e.keyCode == 13){
            $(sbtn).click();
            Event.stop(e);
        }
    }
</script>

This is to prevent a form from being inadvertently submitted.

Capturing The Enter Key Keypress in ASP.NET

aspnet

JavaScript