yii\web\Application::getHomeUrl PHP Method

    public function getHomeUrl()
    {
        if ($this->_homeUrl === null) {
            if ($this->getUrlManager()->showScriptName) {
                return $this->getRequest()->getScriptUrl();
            } else {
                return $this->getRequest()->getBaseUrl() . '/';
            }
        } else {
            return $this->_homeUrl;
        }
    }