CSS: escape() static method

CSS.escape(str)

CSS.escape(".foo#bar"); // "\\.foo\\#bar"
CSS.escape("()[]{}"); // "\\(\\)\\[\\]\\{\\}"
CSS.escape('--a'); // "--a"
CSS.escape(0); // "\\30 ", the Unicode code point of '0' is 30
CSS.escape('\0'); // "\ufffd", the Unicode REPLACEMENT CHARACTER

const element = document.querySelector(`#${CSS.escape(id)} > img`);

const element = document.querySelector(`a[href="#${CSS.escape(fragment)}"]`);