HTML id Attribute
The HTML id attribute is used to specify a unique id for an HTML element. You cannot have more than one element with the same id in an HTML document.
Using The id Attribute
The id
attribute specifies a unique id for an HTML element. The value of the id
attribute must be unique within the HTML document.
The id
attribute is used to point to a specific style declaration in a style sheet. It is also used by JavaScript to access and manipulate the element with the specific id.
The syntax for id is: write a hash character (#), followed by an id name. Then, define the CSS properties within curly braces {}.
In the following example we have an <h1>
element that points to the id name "myHeader". This <h1>
element will be styled according to the #myHeader
style definition in the head section:
Difference Between Class and ID
A class name can be used by multiple HTML elements, while an id name must only be used by one HTML element within the page:
HTML Bookmarks with ID and Links
HTML bookmarks are used to allow readers to jump to specific parts of a webpage.
Bookmarks can be useful if your page is very long.
To use a bookmark, you must first create it, and then add a link to it.
Then, when the link is clicked, the page will scroll to the location with the bookmark.
Example
First, create a bookmark with the id
attribute:
Then, add a link to the bookmark ("Jump to Chapter 4"), from within the same page:
Or, add a link to the bookmark ("Jump to Chapter 4"), from another page:
Using The id Attribute in JavaScript
The id
attribute can also be used by JavaScript to perform some tasks for that specific element.
JavaScript can access an element with a specific id with the getElementById()
method:
Summary
The
id
attribute is used to specify a unique id for an HTML elementThe value of the
id
attribute must be unique within the HTML documentThe
id
attribute is used by CSS and JavaScript to style/select a specific elementThe value of the
id
attribute is case sensitiveThe
id
attribute is also used to create HTML bookmarksJavaScript can access an element with a specific id with the
getElementById()
method
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