I have a drop down box on my website that lets you select your theme. The problem is that I can't figure out how to implement it. Here's the javascript:

//selects the select element
let selectTheme = document.querySelector("#select-theme");
//selects the stylesheet
let style = document.querySelector("#pagestyle");


selectTheme.addEventListener('onchange', () => {
  if (selectTheme.value == "dark") {
    style.setAttribute("href", "./css/style.css");
  }
  if (selectTheme.value == "light") {
    style.setAttribute("href", "./css/style2.css");
  }
  console.log(selectTheme.value);
})

HTML:

<link rel="stylesheet" type="text/css" href="" id="pagestyle">

<div class="selection-box">
      <select class="select-theme" name="selectTheme" id="select-theme">
        <option value="dark" id="dark">dark</option>
        <option value="light" id="light">light</option>
      </select>
    </div>

The even listener itself doesn't seem to work, as it doesn't print out the drop down value.

Also note that this isn't all of my HTML. I just copied and pasted the relevant elements.