Jade\Compiler\AttributesCompiler::getAttributeValue PHP Метод

    protected function getAttributeValue($escaped, $key, $value, &$classesCheck, &$valueCheck)
    {
        if ($this->isConstant($value)) {
            $value = trim($value, ' \'"');
            return $value === 'undefined' ? 'null' : $value;
        }
        $json = static::parseValue($value);
        if ($key === 'class') {
            return $json !== null && is_array($json) ? implode(' ', $json) : $this->getClassAttribute($value, $classesCheck);
        }
        return $this->getValueCode($escaped, $value, $valueCheck);
    }