1👍
You can do something like that
function loadDoc2(value) {
alert(value);
}
<input type="submit" onclick="loadDoc2(document.getElementById('shahr-select').value)" value="continue" style="height:50px;">
<select id="shahr-select" style="direction: rtl;width:200px;height:50px;">
<option class="shahr-options" value="1">first</option>
<option class="shahr-options" value="2">second</option>
<option class="shahr-options" value="3">third</option>
</select>
the .value on a select will get the selected value
Source:stackexchange.com