Is it possible check the Accessibility of a page before loading it?

I have a form, running on mobile device using wireless connection. The problem is: not always this connection is avaible and i would like to alert the user when is doing a submit or an unload of the page.

The problem is that the page contains elements doing redirect like this:

<input type="button" value="MyText" onClick="script1;script2;...window.location='mylocation" />

If the user click on this button and the server is not achievable, i will recive some undesiderable errors.

Also if I want to generalize my script i do not know the value of "mylocation" previously.

The page contains elements to submit the Form also:

<input type="submit" name="SUBMIT" value="MyValue" onClick="return eval('validationForm()')" />

For the submitting I'm using the ajaxForm plugin and it works quite well. This is a snippet of code:

Thanks to your answer I found the solution to the problem. That's the code:

 function checkConnection(u,s){
    $.ajax({
        url:u,
        cache:false,
        timeout:3000,
        error: function(jqXHR, textStatus)
        {
            alert("Request failed: " + textStatus ); 
        },
        success: function()
        {
            eval(s);   
        }
    });       
 }      

    $(document).ready(function() {
        // part of the function that checks buttons with redirect
        // for any input that contain a redirect on onClick attribute ("window.locarion=")
        $("input[type=button]").each(function(){
            var script = $(this).attr("onClick"); 
            var url = "";
            var position = script.indexOf("window.location") ;  
            if (position >= 0) {       // case of redirect           
               url = script.substring(position+17, script.lenght);
               url = url.split("\'")[0];
               url = "\'"+url+"\'"; // that's my url
               script = "\""+script+"\""; // that's the complete script
               $(this).attr("onClick","checkConnection("+url+","+script+")");
            }
        });
        // part of the function that checks the submit buttons (using ajaxForm plugin)
        var is_error = false;
        var options = {
            error: function() {                    
                if (alert("Error Message")==true) {
                }  
                is_error = true;                     
            },
            target: window.document,
            replaceTarget: is_error,
            timeout:   3000
        };
        $("#myForm").ajaxForm(options);
    });

I hope that this will be usefull.