How Can I Detect HTML Element Overflow Using JavaScript?

Examining Overflow Status of an Element

When working with HTML elements, determining if their content extends beyond their designated boundaries is often essential. This enables developers to implement functionalities like displaying overflow indicators and adjusting layout accordingly.

One approach to achieve this is by utilizing the isOverflown() function, which assesses the overflow status of a DOM element. It evaluates both vertical and horizontal overflow conditions, returning a boolean value:

function isOverflown(element) {
  return element.scrollHeight > element.clientHeight || element.scrollWidth > element.clientWidth;
}

This function can be employed in various scenarios. For instance, in the use case mentioned, you could utilize it to discern whether an element with a height limitation of 300px has content that exceeds that height. If overflow is detected, you can then display a "more" button; otherwise, hide it.

To demonstrate the utility of isOverflown(), consider the following JavaScript snippet:

var elements = document.getElementsByClassName('demos');
for (var i = 0; i < elements.length; i++) {
  var element = elements[i];
  element.style.borderColor = (isOverflown(element) ? 'red' : 'green');
  console.log("Element #" + i + " is " + (isOverflown(element) ? '' : 'not ') + "overflown.");
}

CSS for this demonstration:

.demos {
  white-space: nowrap;
  overflow: hidden;
  width: 120px;
  border: 3px solid black;
}

HTML:

<div class='demos'>This is some text inside the div which we are testing</div>
<div class='demos'>This is text.</div>

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