Difference between class and ID selector in jQuery

 In jQuery, class and ID selectors are used to select and manipulate elements in the Document Object Model (DOM) based on their attributes. However, they have distinct differences in terms of how they select elements and their application:

Class Selector ($(".class-name")):

Syntax: To select elements by their class, you use the .class-name syntax, where class-name is the name of the CSS class you want to target.

Selection: Class selectors select all elements that have a specific CSS class applied to them. This means that if multiple elements share the same class, all of them will be selected.

Usage: Class selectors are typically used when you want to apply the same behavior or style to multiple elements with a common class.

Example:

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// Select all elements with the class "button"

$(".button").click(function() {

    // Perform some action

});

ID Selector ($("#element-id")):

Syntax: To select elements by their ID, you use the #element-id syntax, where element-id is the unique ID assigned to the element you want to target.

Selection: ID selectors select a single element with the specified ID. IDs must be unique within a web page, so there should be only one element with a given ID.

Usage: ID selectors are used when you want to target a specific element on the page for a unique operation or manipulation.

Example:

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// Select the element with the ID "header"

$("#header").addClass("highlight");

Key Differences:

Uniqueness: Class selectors can select multiple elements with the same class, while ID selectors target a single, unique element with a specific ID.

Performance: ID selectors are generally faster than class selectors because they exploit the uniqueness of IDs, making the search more efficient.

Applicability: Use class selectors when you want to apply a behavior or style to multiple elements with a shared class. Use ID selectors when you need to interact with or manipulate a specific, unique element.

CSS Specificity: In terms of CSS specificity, IDs have higher specificity than classes. This means that rules applied to IDs will override rules applied to classes, which can be important for styling.

In summary, understanding the differences between class and ID selectors in jQuery is essential for efficiently selecting and manipulating elements in your web applications. Select classes when you want to work with multiple elements sharing the same class, and use IDs when you need to interact with a unique element on the page.

main difference between class and Id selector in jQuery is that class selector starts with dot (.) while ID selector starts with pound (#) e.g.

$(".articles") will select all elements which has class articles applied on them

$(#article) will only select the element with id article, remember a webpage cannot have elements with duplicate id, which means on id can only be used by one element. 

Though jQuery allows you to select elements using many differnt ways, finding elmeent using tag name is the most common one e.g. $("p") can be used to find all paragraph text or $("li") can be used to find all list tags in the page, but sometime you need to little bit of flexibility. 

1) ID Selector is fastest selector in jQuery.

2) ID's should be unique on the page, when you have multiple elements with same ID's, jQuery selects only the first one. That's because it doesn't have to bother looking for others as there isn't supposed to be any more - that might explain the weird behaviour you're experiencing.

3) ID selector always return a single element but class selector can return more than one elements. This happens becasue ID is uninuqe in a page and cannot be shared between elements but class can be shared between multiple elements. 

4) Query searches for elements from right to left then walks up the DOM tree to see if they match the next selector going left..