| const ISO_10646_CHARACTERS = /\\[0-9a-f]{1,6}(\\r\\n|[ \t\r\n\f])?/gi; |
| const SINGLE_ESCAPED_CHARACTERS = /\\./g; |
| const NON_WORD_OR_DASH = /[^\w-]/; |
| const DIGIT = /\d/; |
| |
| /** |
| * Returns whether a string is a valid CSS identifier |
| * (i.e. only alphanumeric characters, `-`, and `_`; |
| * does not have a leading digit, leading dash followed by digit, or two leading dashes) |
| * furthermore, any escaped or ISO 10646 characters are allowed. |
| * @see https://www.w3.org/TR/CSS2/syndata.html#value-def-identifier |
| * @param {string} ident |
| * @returns {boolean} |
| */ |
| export default function isValidIdentifier(ident) { |
| if (!ident || ident.trim() === '') { |
| return false; |
| } |
| |
| // trims, removes ISO 10646 characters, and singly-escaped characters |
| const trimmedIdent = ident |
| .trim() |
| .replace(ISO_10646_CHARACTERS, '') |
| .replace(SINGLE_ESCAPED_CHARACTERS, ''); |
| |
| if (NON_WORD_OR_DASH.test(trimmedIdent)) { |
| return false; |
| } |
| |
| if (DIGIT.test(trimmedIdent.charAt(0))) { |
| return false; |
| } |
| |
| if (trimmedIdent.charAt(0) === '-' && DIGIT.test(trimmedIdent.charAt(1))) { |
| return false; |
| } |
| |
| return true; |
| } |
