Get other user's first_name by their keycloak user id

I have fetched the list of my application user objects(not all realm users) from my API server. User object contains user’s id , user’s group, and some other application specific details. I want to show this in my web frontend. How do I get user’s name by their id? I am also using keycloak-js module in VueJs application. But I couldn’t find any inbuilt method in keycloak-js to achieve my need. Please help me to get user name by their id.