<div class="boxes">
  <div class="box">1</div>
  <div id="targetBox" class="box">2</div>
</div>

<div class="controls">
  <button id="btn">Toggle Box 2 Position</button>
</div>
:root {
  --spacer: 1.5rem;
}

body {
  align-items: center;
  background: #333;
  display: flex;
  flex-direction: column;
  justify-content: center;
  height: 100vh;
  padding: var(--spacer);
}

.boxes {
  background: rgba(255, 255, 255, 1);
  display: flex;
  padding: var(--spacer);
}
.box {
  align-items: center;
  display: flex;
  height: 200px;
  justify-content: center;
  width: 200px;
}
.box:first-child {
  background: #ff8a00;
}
.box:nth-child(2) {
  background: #e52e71;
}

.absolute {
  position: absolute;
}

.controls {
  margin-top: var(--spacer);
}
let box = document.getElementById("targetBox").classList;
let button = document.getElementById("btn");

function positionBox() {
  if (box.contains("absolute")) {
    box.remove("absolute");
  } else {
    box.add("absolute");
  }
}

button.addEventListener("click", positionBox);

External CSS

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External JavaScript

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