JSFiddle - React, Tailwind, and code Playground

HTML

<div class="form_productselect">
    <div class="form_item"> 
        Select Product: 
        <select id="product_id" name="product_id">
            <option value="0" selected="selected">--</option>
            <option value="1213" >FOO</option>
            <option value="1315" >BAR</option>
        </select>
    </div>
</div>

<div class="form_contentselect">
    <div class="form_item"> 
        Select Content: 
        <select id="content_id" name="content_id">
            <option value="0" selected="selected">--</option>
            <option value="1213-3973" class="opt-1213" >FOO - 100 points</option>
            <option value="1213-3953" class="opt-1213" >FOO - 1000 points</option>
            <option value="1315-3965" class="opt-1315" >BAR - 100 points</option>
            <option value="1315-3949" class="opt-1315" >BAR - 1000 points</option>
        </select>
    </div>
</div>

JavaScript

$(document).ready(function() {
    var allOptions = $('#content_id option').clone();
    $('#product_id').change(function() {
        var val = $(this).val();
        $('#content_id').html(allOptions.filter('.opt-' + val));
    });
});