check if any select box has changed after button click
<p>I want to check a group of select boxes and see if they changed after a button has clicked.</p>

<pre><code>&lt;select name="data[model][that]" class="location_dropdown"&gt;
    &lt;option value="value1"&gt;value 1&lt;/option&gt;
    &lt;option value="value2"&gt;value 2&lt;/option&gt;
    &lt;option value="value3" selected="selected"&gt;value 3&lt;/option&gt;
&lt;/select&gt;

&lt;select name="data[model][that]" class="location_dropdown"&gt;
    &lt;option value="value1"&gt;value 1&lt;/option&gt;
    &lt;option value="value2" selected="selected"&gt;value 2&lt;/option&gt;
    &lt;option value="value3"&gt;value 3&lt;/option&gt;
&lt;/select&gt;

&lt;select name="data[model][other]" class="location_dropdown"&gt;
    &lt;option value="value1" selected="selected"&gt;value 1&lt;/option&gt;
    &lt;option value="value2"&gt;value 2&lt;/option&gt;
    &lt;option value="value3"&gt;value 3&lt;/option&gt;
&lt;/select&gt;

$(document).ready(function() {

    $('#update-selected-btn').click(function(){
        $('.location_dropdown').each(function(){



        });
    });

    if state hasnt changed on any drop downs alert("nothing selected")

});
</code></pre>

<p>Obviously cant use onchange as I want to check for change when button click triggered. I was thinking about maybe building a array of values and checking them against each other, but wonder if there is another solution.</p>

<p><strong>UPDATE:</strong></p>

<p>I did attempt this, but syntax isnt right.</p>

<pre><code>$('.location_dropdown').each(function(){
    if ($(this + " option:selected").prop('selected') == 'selected'){
       changed++;
    }
});
</code></pre>
