For more details, see Cypress catalogue of events

• cypress-on-spec.cy.js shows how we can add a property to every window object before the app load using Cypress.on('window:before:load', ...) event listener
• cy-on-spec.cy.js shows how to add a property to every window object before the app loads using cy.on('window:before:load', ...) event listener.

• recipe "Handling errors" from the Fundamentals recipes