There are several possibilities, for example in combination with JavaScript and event listening prestashop.on('updateCart ....
A header hook is added to the module and javascript is connected + messages are defined.
E.g.:
Module
/* install setion */ && $this->registerHook('displayHeader'); /* function */ public function hookDisplayHeader() { $this->context->controller->addJS(_PS_MODULE_DIR_.$this->name.'/views/js/front/front.js'); $jsDef = [ 'custom_success_message' => $this->l('Succes'), ]; Media::addJsDef($jsDef); }
JS
prestashop.on( 'updateCart', function (event) { var myDiv = document.createElement('div'); myDiv.setAttribute('id', 'myDiv'); myDiv.setAttribute('style', 'display:block; padding:5px; color:black; background: green; font-size:1.2em; position:sticky; top:10px; right:10px; text-align:center;'); myDiv.textContent = custom_success_message; document.getElementById('header').appendChild(myDiv); setTimeout(function() { $('#mydiv').remove(); }, 3000); } }