submit button need alert if value not select rather then send to blank page

[jonnyfreak]

I have a product page that sends to a product detail page, The detail page also has all other products from the catagory.. The problem is when they land on the page it shows their selected product but in order for the information to pass to the cart they need to select the product first, even though they are already on the page (because there are other produts there) at present if they do not choose their product and just hit select it sends them to a blank page. i need to to prompt and say " please select design first)

this is the form

<form id="FormName" action="" method="get" name="FormName">
            <table>
              <tr valign="middle">
                <td width="30" height="40" class="meduimTXT">1.</td>
                <td width="190" align="left"><div align="left">
                  <select name="ID" class="text" id="selectName">
                    <option value="Select Design">Select Design</option>
                    <?php
                                        mysql_select_db($database_beau, $beau);
                                        $query = sprintf("SELECT * FROM beauProd WHERE CatID = '%s'", GetSQLValueString($row_Recordset1['CatID'], "int"));
                                        $results = mysql_query($query, $beau) or die(mysql_error());
                                        $productsInCategory = array();
                                        while($row = mysql_fetch_array($results)){
                                                  $productsInCategory[] = $row['ID'];
                                                  ?>
                    <option value="<?php echo $row['ID']; ?>"><?php echo $row['name']; ?></option>
                    <?php
                                        }
                                        ?>
                  </select>
                </div></td>
                <td width="190" align="left"><input type="image" src="../images/select design.gif" border="0" name="button" id="button" value="select new design" /></td>
              </tr>
            </table>
          </form>

thanks in advance

[bernie1227]

Wouldn't it be easier to simply deactivate the button until they have selected a product?

What you could do in answer to your question, is set up a JavaScript to alert onclick if no product is selected using a simple if/else.

[jonnyfreak]

ideally yes deactivate the button until an option is selected.

how would i go about do that?
thanks

[bernie1227]

well in order to actually deactivate the button, you should use:

function disable(){
document.getElementById('button').disabled = true; 
}

so simply check if one of the products is selected and then trigger the function if it's not.

[jonnyfreak]

I have tried the following but am sure its wrong

<script type='text/javascript'>
function disable(){
document.getElementById('button').disabled = true; 
}
</script>
<form id="button" method="post" action="" onclick="function()">
    <p>
        <select id="ad_type" name="ad_type">
            <option value="" selected="selected">Select premium ad type</option>
            <option value="<?php echo TYPE_USER;?>">Featured Agent</option>
        </select>

[jonnyfreak]

thats wrong on my behalf not your. Thanks in advance

[jonnyfreak]

thinking about it i would need the alert with an if/else statement

[bernie1227]

you may want something like:

<script type='text/javascript'>
function disable(){
if(ID.value == 'Select Design'){
document.getElementById('button').disabled = true; 
}
}
</script>
<form id="button" method="post" action="" onclick="disable()">
<p>
<select id="ad_type" name="ad_type">
<option value="" selected="selected">Select premium ad type</option>
<option value="<?php echo TYPE_USER;?>">Featured Agent</option>
</select>

[jonnyfreak]

thanks for that, but the process of the form is they select a design (then have to submit that in order to give the values of that design) then choose the size below then send to cart so the alert would be better.

[bernie1227]

<script type='text/javascript'>
function disable(){
if(ID.value == 'Select Design'){
alert('please select an option');
}
}
</script>
<form id="button" method="post" action="" onclick="disable()">
<p>
<select id="ad_type" name="ad_type">
<option value="" selected="selected">Select premium ad type</option>
<option value="<?php echo TYPE_USER;?>">Featured Agent</option>
</select>