getComputedStyle()The getComputedStyle() global method returns an CSSStyleDeclaration object that represents all CSS declarations applied to a given element.cssomCSS object modelswidely2015-07-292018-01-29https://drafts.csswg.org/cssom-1/#extensions-to-the-window-interfacegetcomputedstylehttps://developer.mozilla.org/docs/Web/API/Window/getComputedStyleapi.Window.getComputedStyleapi.Window.getComputedStyle.pseudo_element_supporthttps://nowyoucanuse.com/features--get-computed-style.html