/**
 * Determine whether a passed text content is a collapsed whitespace.
 *
 * In HTML, whitespaces at the start and end of elements and outside elements are ignored.
 * There are two types of whitespaces in HTML:
 * - Visible ( )
 * - Invisible (regular trailing spaces, tabs, etc)
 * @see https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model/Whitespace
 * @see https://www.w3.org/TR/css-text-3/#white-space-processing
 * @param textContent — any string, for ex a textContent of a node
 * @returns True if passed text content is whitespace which is collapsed (invisible) in browser
 */
export declare function isCollapsedWhitespaces(textContent: string): boolean;