Here is a detailed explanation.
If you want to consistently style multiple elements throughout the page/site, use a class. When there is a single element on the page that requires a specific style, use an ID. A class represents a type of item, while an ID is the unique name of an item.
UPDATE:
CSS ignores
In terms of CSS
, there is nothing exclusive to an ID
that cannot be achieved with a Class
, and vice versa. Despite trying to troubleshoot by swapping these values in my early days of learning CSS
, it didn't make any difference as CSS
remains indifferent.
Javascript makes a distinction
Those well-versed in JavaScript
are likely aware of the variances between classes
and ID's
. JavaScript
relies on having only one page element with a particular identifier for functions like getElementById
to function reliably. With jQuery
, adding or removing classes
from page elements is seamless due to its native functionality, unlike ID's
which lack such capability. Manipulating these values using JavaScript
would lead to more issues than solutions.
The Documentation emphasizes the necessity for the ID attribute to be unique within a page:
This attribute bestows a name upon an element, requiring it to be exclusive in a document. Noncompliance with this rule renders your HTML invalid.
Hence, getElementById()
in JavaScript
should invariably return a singular element to maintain consistency. Though it's possible to assign identical IDs to multiple elements, it's strongly advised against to prevent unpredictability across different browsers.