Is there an opposite to display:none?

display: none doesn’t have a literal opposite like visibility:hidden does.

The visibility property decides whether an element is visible or not. It therefore has two states (visible and hidden), which are opposite to each other.

The display property, however, decides what layout rules an element will follow. There are several different kinds of rules for how elements will lay themselves out in CSS, so there are several different values (block, inline, inline-block etc — see the documentation for these values here ).

display:none removes an element from the page layout entirely, as if it wasn’t there.

All other values for display cause the element to be a part of the page, so in a sense they’re all opposite to display:none.

But there isn’t one value that’s the direct converse of display:none - just like there's no one hair style that's the opposite of "bald".

A true opposite to display: none there is not (yet).

But display: unset is very close and works in most cases.

From MDN (Mozilla Developer Network):

The unset CSS keyword is the combination of the initial and inherit keywords. Like these two other CSS-wide keywords, it can be applied to any CSS property, including the CSS shorthand all. This keyword resets the property to its inherited value if it inherits from its parent or to its initial value if not. In other words, it behaves like the inherit keyword in the first case and like the initial keyword in the second case.

(source: https://developer.mozilla.org/docs/Web/CSS/unset)

Note also that display: revert is currently being developed. See MDN for details.

When changing element's display in Javascript, in many cases a suitable option to 'undo' the result of element.style.display = "none" is element.style.display = "". This removes the display declaration from the style attribute, reverting the actual value of display property to the value set in the stylesheet for the document (to the browser default if not redefined elsewhere). But the more reliable approach is to have a class in CSS like

.invisible { display: none; }

and adding/removing this class name to/from element.className.