JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <input type="text" id="numPoint" />
    <input type="button" id="addPoints" value="Add Points" />
</div>
<form>
    <table id="polygons"></table>
    <input type="submit" value="submit" />
</form>

JavaScript

$('#addPoints').click(function(){
    var num = $('#numPoint').val()
    
    if(num > 0)
    {
        for(i=0;i<num;i++)
        {
            html = '<tr>';
            html += '<td><input type="text" name="ply[' + i + ']" /></td>';
            html += '<td><input type="text" name="pnt[' + i + ']" /></td>';
            html += '<td><input type="text" name="y[' + i + ']"/></td>';
            html += '<td><input type="text" name="x[' + i + ']" /></td>';
            html += '</tr>';
    
            $('#polygons').append(html);
            html = "";       
        }                       
    }
    else
    {
        alert("Please declare number of points you want to enter");                    
    }
});