JSFiddle - React, Tailwind, and code Playground

HTML

<form>
    <table>
    <tr><td><input type="text" value="50" name="myvar[]" /></td></tr>

    <!-- This button will clone the previous set of form elements -->
    <tr><input type="button" value="Add New Line" onclick="this.getParent('tr').getPrevious('tr').clone().inject(this.getParent('tr'), 'before')" /></tr>
    </table>
</form>