ElementList<Element> querySelectorAll(String selectors)

Finds all descendant elements of this document that match the specified group of selectors.

Unless your webpage contains multiple documents, the top-level querySelectorAll method behaves the same as this method, so you should use it instead to save typing a few characters.

selectors should be a string using CSS selector syntax.

var items = document.querySelectorAll('.itemClassName');

For details about CSS selector syntax, see the CSS selector specification.

Source

ElementList<Element> querySelectorAll(String selectors) =>
    document.querySelectorAll(selectors);