JSFiddle - React, Tailwind, and code Playground

HTML

<select name="mdocs[cat][0]" class="hioooo">
    <option value="mdocs-cat-7">1</option>
    <option value="mdocs-cat-22">2</option>
</select>
<select name="mdocs[cat][1]" class="hioooo">
    <option value="mdocs-cat-7">1</option>
    <option value="mdocs-cat-22">2</option>
</select>
<select name="mdocs[cat][3]" id="hioooo">
    <option value="mdocs-cat-7">1</option>
    <option value="mdocs-cat-22">2</option>
</select>
<select name="mdocs[cat][4]" id="hioooo">
    <option value="mdocs-cat-7">1</option>
    <option value="mdocs-cat-22">2</option>
    .....
</select>

JavaScript

var x = document.getElementsByClassName("hioooo");
var i;
for (i = 0; i < x.length; i++) {
    x[i].selectedIndex = 1;
}