Cypress.dom.isHidden()

To see whether a DOM element is hidden, use Cypress.dom.isHidden().

var hiddenP = Cypress.$('.dom-p p.hidden').get(0)
var visibleP = Cypress.$('.dom-p p.visible').get(0)

// our first paragraph has css class 'hidden'
expect(Cypress.dom.isHidden(hiddenP)).to.be.true
expect(Cypress.dom.isHidden(visibleP)).to.be.false

I'm visible!