Some of the most basic components we can manipulate when it comes to DOM elements are the properties and attributes assigned to those elements.
Most of these attributes are available through JavaScript as DOM node properties. Some of the more common properties are −
className
tagName
id
href
title
rel
src
Consider the following HTML markup for an image element −
<img id = "imageid" src = "image.gif" alt = "Image" class = "myclass"
title = "This is an image"/>
In this element's markup, the tag name is img, and the markup for id, src, alt, class, and title represents the element's attributes, each of which consists of a name and a value.
jQuery gives us the means to easily manipulate an element's attributes and gives us access to the element so that we can also change its properties.
Get Attribute Value
The attr() method can be used to either fetch the value of an attribute from the first element in the matched set or set attribute values onto all matched elements.
Example
Following is a simple example which fetches title attribute of <em> tag and set <div id = "divid"> value with the same value −
<html>
<head>
<title>The jQuery Example</title>
<script type = "text/javascript"
src = "https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js">
</script>
<script type = "text/javascript" language = "javascript">
$(document).ready(function() {
var title = $("em").attr("title");
$("#divid").text(title);
});
</script>
</head>
<body>
<div>
<em title = "Bold and Brave">This is first paragraph.</em>
<p id = "myid">This is second paragraph.</p>
<div id = "divid"></div>
</div>
</body>
</html>
This will produce following result −
Set Attribute Value
The attr(name, value) method can be used to set the named attribute onto all elements in the wrapped set using the passed value.
Example
Following is a simple example which set src attribute of an image tag to a correct location −
<html>
<head>
<title>The jQuery Example</title>
<base href="https://www.howcodex.com" />
<script type = "text/javascript"
src = "https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js">
</script>
<script type = "text/javascript" language = "javascript">
$(document).ready(function() {
$("#myimg").attr("src", "/jquery/images/jquery.jpg");
});
</script>
</head>
<body>
<div>
<img id = "myimg" src = "/images/jquery.jpg" alt = "Sample image" />
</div>
</body>
</html>
This will produce following result −
Applying Styles
The addClass( classes ) method can be used to apply defined style sheets onto all the matched elements. You can specify multiple classes separated by space.
Example
Following is a simple example which sets class attribute of a para <p> tag −
Set the value attribute of every matched element if it is called on <input> but if it is called on <select> with the passed <option> value then passed option would be selected, if it is called on check box or radio box then all the matching check box and radiobox would be checked.
Examples
Similar to above syntax and examples, following examples would give you understanding on using various attribute methods in different situation −
Sr.No.
Selector & Description
1
$("#myID").attr("custom")
This would return value of attribute custom for the first element matching with ID myID.
2
$("img").attr("alt", "Sample Image")
This sets the alt attribute of all the images to a new value "Sample Image".
3
$("input").attr({ value: "", title: "Please enter a value" });
Sets the value of all <input> elements to the empty string, as well as sets The jQuery Example to the string Please enter a value.
4
$("a[href^=https://]").attr("target","_blank")
Selects all links with an href attribute starting with https:// and set its target attribute to _blank.
5
$("a").removeAttr("target")
This would remove target attribute of all the links.
