button hide if input empty

by Keyur Bhatt

HTML

<input type="text" name ="mytxt" id="mytxt"> 
<a href="#" id="btnsubmit" class="btn1">Submit</a>

JavaScript

$('input[name=mytxt]').change(function() { 
if($(this).val() == "") {        
        $("#btnsubmit").hide();
    } else {
        $("#btnsubmit").show();
    }
});