Replace Tokens with Word Boundary in a Text in Unicode and ASCII

replace_tokens_word_boundary_unicode_ascii.js

/**
 * Replace tokens in text
 * It support both Unicode and ASCII Regex for word boundaries
 * @param {*} isUnicode true to use Unicode Regex
 * @param {*} text input text
 * @param {*} tokens Tokens indexes
 * @param {*} words Words
 * @param {*} expr Replacement 
 */
var replaceTokens = function (isUnicode, text, tokens, words, expr) {
    const seen = new Map();
    var pattern = "\\b($1)\\b";
    if (isUnicode) pattern = "(?<!\\S)$1(?!\\S)";
    tokens.forEach((token, index) => {
        var word = words[index];
        var escaped = word.replace(/[\-\[\]{}()*+?.,\\\^$|#\s]/g, "\\$&");
        var wordRegex = new RegExp(pattern.replace('$1', escaped), "g");
        var match = null;
        while ((match = wordRegex.exec(text)) !== null) {
            if (match.index > (seen.get(word) || -1)) {
                var wordEnd = match.index + word.length - 1;
                var replacement = expr[token].replace('$1', escaped);
                text = text.slice(0, match.index) + replacement + text.slice(wordRegex.lastIndex);
                seen.set(word, wordEnd);
                break;
            }
        }
    });
    return text;
}//replaceTokens