add()

The jQuery add() function is used to add elements to a set of matched elements in a jQuery object. This method is useful for combining elements from different selectors or different parts of the document into a single jQuery collection, which can then be manipulated or iterated over in a unified way.

The basic syntax of the add() function is:

$(selector).add(elements);

Where:

• selector - the initial jQuery selector
• elements - the elements to be added to the jQuery object. It can be a string representing a selector, a Document Object Model element, an HTML string or another jQuery object.

The add() function is often used to combine elements from multiple selectors such as:

$("div").add("p");

This selects all <div> elements and then adds all <p> elements to the same jQuery object. If you need to apply the same style or event handlers to a group of elements that don't share the same parent or class, you can use add() to group them together:

$("#myDiv").add(".myClass").css("background-color", "yellow");

This will change the background color of both the element with id myDiv and all elements with the class myClass.

If add() is used to handle user-supplied input or content from untrusted sources without proper validation and sanitization, there could be a risk of Cross-Site Scripting attacks. For example, if HTML content created based on user input is added to the DOM using add(), it could include malicious scripts.