Calling getParams() in Magento2

You can directly call inside phtml file like below,

$blockObject= $block->getLayout()->createBlock('Namespace\Vendor\Block\YourBlock');

$params = $blockObject->getRequest()->getParams(); 

In controllers and blocks you have direct access to the request object:

$this->getRequest()->getParams()

Anywhere else, you have to add \Magento\Framework\App\RequestInterface as constructor parameter if it is not there yet, and assign it to $this->request. Then you can use

$this->request->getParams()

Fetch All Posted data on a controller in a variable

$data = $this->getRequest()->getParams();

Use a helper on phtml

$this->helper('\Helloworld\CustomModule\Helper\Data')->getCustomdata($data);