JSFiddle - React, Tailwind, and code Playground
HTML
<div id="fooTest">
<select name="foo_1">
<option value="bar" selected>bar</option>
<option value="foo">foo</option>
</select>
<select name="foo_2">
<option value="bar" selected>bar</option>
<option value="foo">foo</option>
</select>
</div>
<div id="output"
</div>
JavaScript
var count = $("#fooTest").find("select[name^=foo] > option[value=bar]:selected").length;
$("#output").html(count);