Master the unique identity in HTML with the id attribute! Explore examples for targeted styling and interactive functionality, enhancing precision in web design.
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.
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:
<!DOCTYPE html>
<html>
<head>
<style>
#myHeader {
background-color: lightblue;
color: black;
padding: 40px;
text-align: center;
}
</style>
</head>
<body>
<h1 id="myHeader">My Header</h1>
</body>
</html>
Note: The id name is case sensitive!
Note: The id name must contain at least one character, cannot start with a number, and must not contain whitespaces (spaces, tabs, etc.).
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:
<style>
/* Style the element with the id "myHeader" */
#myHeader {
background-color: lightblue;
color: black;
padding: 40px;
text-align: center;
}
/* Style all elements with the class name "city" */
.city {
background-color: tomato;
color: white;
padding: 10px;
}
</style>
<!-- An element with a unique id -->
<h1 id="myHeader">My Cities</h1>
<!-- Multiple elements with same class -->
<h2 class="city">London</h2>
<p>London is the capital of England.</p>
<h2 class="city">Paris</h2>
<p>Paris is the capital of France.</p>
<h2 class="city">Tokyo</h2>
<p>Tokyo is the capital of Japan.</p>
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.
First, create a bookmark with the id
attribute:
<h2 id="C4">Chapter 4</h2>
Then, add a link to the bookmark ("Jump to Chapter 4"), from within the same page:
<a href="#C4">Jump to Chapter 4</a>
Or, add a link to the bookmark ("Jump to Chapter 4"), from another page:
<a href="html_demo.html#C4">Jump to Chapter 4</a>
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:
Use the id
attribute to manipulate text with JavaScript:
<script>
function displayResult() {
document.getElementById("myHeader").innerHTML = "Have a nice day!";
}
</script>
id
attribute is used to specify a unique id for an HTML elementid
attribute must be unique within the HTML documentid
attribute is used by CSS and JavaScript to style/select a specific elementid
attribute is case sensitiveid
attribute is also used to create HTML bookmarksgetElementById()
method#html