How are dynamic transitions achieved from a frontal point of view?

See, for example, the sign-in experience in Google Accounts, where you pass & # 39; Enter email & # 39; a & # 39; Enter password & # 39; through a dynamic transition without problems without page refresh

How can I talk to a front-end designer to achieve this type of interaction? Is it just & # 39; javascript & # 39 ;?

Very often, I find the developers converting UX specifications for features like this in basic page renewals, and I want to have the language to tell them about it

Thank you