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