How Can I Programmatically Detect HTML Element Content Overflow Without Scrollbars?

Detecting HTML Element Content Overflow Without Scrollbars

Knowing if an HTML element's content exceeds its bounds can be crucial for various scenarios. However, checking for overflow can be tricky, especially when the element has its overflow property set to "visible" and lacks scrollbars.

To overcome this challenge, we can leverage JavaScript to determine overflow. One common approach is to compare the element's client[Width/Height] with scroll[Width/Height]. However, when overflow is set to "visible," these values become identical, hindering accurate detection.

Detecting Overflow Programmatically

To account for this peculiarity, we can employ a detection routine that temporarily modifies the element's "overflow" style:

// Determines if the passed element is overflowing its bounds,
// either vertically or horizontally.
// Will temporarily modify the "overflow" style to detect this
// if necessary.
function checkOverflow(el) {
  var curOverflow = el.style.overflow;

  if (!curOverflow || curOverflow === "visible") {
    el.style.overflow = "hidden";
  }

  var isOverflowing = el.clientWidth < el.scrollWidth || el.clientHeight < el.scrollHeight;

  el.style.overflow = curOverflow;

  return isOverflowing;
}

The checkOverflow function:

1. Stores the current overflow property value in curOverflow.
2. Sets overflow to "hidden" (without scrollbars) if it's not set or is "visible." This ensures accurate overflow detection.
3. Compares the element's client dimensions (clientWidth, clientHeight) with its scroll dimensions (scrollWidth, scrollHeight). If any of these dimensions are smaller, it indicates overflow.
4. Resets the overflow property to its original value.
5. Returns the isOverflowing boolean result.

This routine has been tested in major browsers such as Firefox, Internet Explorer, and Chrome, providing reliable overflow detection regardless of overflow settings or the presence of scrollbars.

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