JSFiddle - React, Tailwind, and code Playground

HTML

<div id="n0">-</div>
    <div id="n1">-</div>
    <div id="n2">-</div>
    <input type="button" value="easy" onClick="loadGame('easy')"/>
    <input type="button" value="normal" onClick="loadGame('normal')"/>
    <input type="button" value="hard" onClick="loadGame('hard')"/>

JavaScript

function loadGame(level) {
    var values;
    switch (level) {
    case 'hard':
        values = [7, 8, 9];
        break;
    case 'normal':
        values = [4, 5, 6];
        break;
    default:
        //easy
        values = [1, 2, 3];
    }
    for (i = 0; i <= values.length; i++) {
        document.getElementById('n' + i).innerHTML = values[i];
    }
}