JavaScript querySelectorAll()

The querySelectorAll() method in JavaScript is used to select all elements that match a CSS selector.
The syntax for the querySelectorAll() method is:

document.querySelectorAll(selector);
 

where selector is a CSS selector that specifies the elements to select.

For example, the following code will select all button elements with class = “btn”:

const elements = document.querySelectorAll('.btn');

The querySelectorAll() method returns a NodeList object that contains all of the elements that match the selector. A NodeList is an array-like object that represents a collection of DOM nodes.

Here are some examples of CSS selectors that can be used with the querySelectorAll() method:

• div: Selects all div elements.
• .myClass: Selects all elements with the class myClass.
• #myElement: Selects the element with the ID myElement.
• a[href="https://www.google.com/"]:hover: Selects all a elements with the href attribute that is equal to https://www.google.com/ and that are currently being hovered over.

The querySelectorAll() method is a powerful tool that can be used to select elements in the DOM. It is often used in conjunction with other DOM methods, such as getElementById() and querySelector().

differences between querySelector() and querySelectorAll()

querySelectorAll() is more flexible than querySelector() because it can be used to select multiple elements, not just a single element. However, querySelector() is more efficient because it does not have to parse the entire DOM to find the elements.

The best method to use depends on the specific situation. If you need to select multiple elements that match a CSS selector, then querySelectorAll() is the best option. If you need to select a single element that matches a CSS selector, then querySelector() is the best option.