framework/helpers/BaseHtml.php
public static function escapeJsRegularExpression($regexp)
    {
        $pattern = preg_replace('/\\\\x\{?([0-9a-fA-F]+)\}?/', '\u$1', $regexp);
        $deliminator = substr($pattern, 0, 1);
        $pos = strrpos($pattern, $deliminator, 1);
        $flag = substr($pattern, $pos + 1);
        if ($deliminator !== '/') {
            $pattern = '/' . str_replace('/', '\\/', substr($pattern, 1, $pos - 1)) . '/';
        } else {
            $pattern = substr($pattern, 0, $pos + 1);
        }
        if (!empty($flag)) {
            $pattern .= preg_replace('/[^igmu]/', '', $flag);
        }

        return $pattern;
    }
public static function escapeJsRegularExpression($regexp)
    {
        $pattern = preg_replace('/\\\\x\{?([0-9a-fA-F]+)\}?/', '\u$1', $regexp);
        $deliminator = substr($pattern, 0, 1);
        $pos = strrpos($pattern, $deliminator, 1);
        $flag = substr($pattern, $pos + 1);
        if ($deliminator !== '/') {
            $pattern = '/' . str_replace('/', '\\/', substr($pattern, 1, $pos - 1)) . '/';
        } else {
            $pattern = substr($pattern, 0, $pos + 1);
        }
        if (!empty($flag)) {
            $pattern .= preg_replace('/[^igmu]/', '', $flag);
        }

        return $pattern;
    }
Escapes regular expression to use in JavaScript.
@param string $regexp the regular expression to be escaped.
@return string the escaped result.
@since 2.0.6