JSFiddle - React, Tailwind, and code Playground

HTML

<h1>
Map Generator
</h1>
<table>
  <tr>
    <td>
      <button id="randomize" type="button">Randomize</button>
    </td>
    <td>Frequency</td>
    <td>Land Area</td>
    <td>Richness</td>
    <td>Starting Area</td>
  </tr>
  <tr>
    <td>Terrain segments</td>
    <td>
      <select>
        <option>Very Low</option>
        <option>Low</option>
        <option selected>Normal</option>
        <option>High</option>
        <option>Very High</option>
      </select>
    </td>
    <td>
      <select>
        <option>Very Small</option>
        <option>Small</option>
        <option selected>Medium</option>
        <option>Big</option>
        <option>Very Big</option>
        <option>Water only in Starting Area</option>
      </select>
    </td>
    <td>
      <select>
        <option>Desert</option>
        <option>Very Dry</option>
        <option>Dry</option>
        <option selected>Regular</option>
        <option>Humid</option>
        <option>Very Humid</option>
        <option>Tropical</option>
      </select>
    </td>
    <td>
      <select>
        <option>Desert bias</option>
        <option>Dirt bias</option>
        <option>Plains bias</option>
        <option selected>Normal</option>
        <option>Forest bias</option>
        <option>Jungle bias</option>
      </select>
    </td>
  </tr>
  <tr>
    <td>Iron ore</td>
    <td>
      <select>
        <option>Very Low</option>
        <option>Low</option>
        <option selected>Normal</option>
        <option>High</option>
        <option>Very High</option>
      </select>
    </td>
    <td>
      <select>
        <option>None</option>
        <option>Very Small</option>
        <option>Small</option>
        <option selected>Medium</option>
        <option>Big</option>
        <option>Very Big</option>
      </select>
    </td>
    <td>
      <select>
        <option>Very Poor</option>
        <option>Poor</option>
        <option selected>Regular</option>
        <option>Good</option>
       ...

JavaScript

document.getElementById("randomize").onclick = function() {

  var dropdowns = document.getElementsByTagName("select");

  for (var i = 0; i < dropdowns.length; i++) {

    dropdowns[i].selectedIndex = Math.floor((Math.random() + Math.random() + Math.random()) / 3 * dropdowns[i].options.length);
  }

  document.getElementById("seed").value = Math.floor(Math.pow(2, 32) * Math.random());
}