How Can I Accurately Access the `display` Property of DOM Elements?

Accessing the Display Property of DOM Elements Accurately

Retrieving the display property of DOM elements can seem straightforward, but unexpected results may arise. Consider the following example:

var a = (document.getElementById('a')).style;
alert(a.display);

This alert may display an empty string instead of the expected "none" value. Why is this happening?

The issue lies in the difference between the CSS attribute value and the applied style.

CSS Attribute Value vs. Applied Style

The .style.* properties, including .display, map to the CSS attribute value, not to the applied style. The applied style reflects the result of CSS cascading and might differ from the attribute value.

In the given example, the display property of element "a" is set to "none" in the CSS attribute style:

a {
  display: none;
}

However, the applied style may be different due to external stylesheets or dynamic modifications.

Using getComputedStyle

To retrieve the applied style correctly, use the getComputedStyle() method. It takes an element as an argument and returns a CSSStyleDeclaration object containing the computed CSS styles.

var a = (document.getElementById('a'));
alert(getComputedStyle(a).display);  // Displays "none" as expected

Alternative Approach: Class Toggles

As an alternative, consider using CSS classes to toggle the visibility of elements. This approach separates the presentation from the logic and avoids the need to manipulate CSS attributes directly.

.hidden {
  display: none;
}

var p = document.getElementById('p');
p.classList.toggle('hidden'); // Toggles the display property

By using getComputedStyle or class toggles, you can accurately access and control the display property of DOM elements.

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