Need to build custom solution using JITSI low level javascript

How can I build a custom solution using JITSI low level JavaScript library (no iframe) that supports private audio, video, screen-sharing and chat functionality one to one. Like there will be one admin account (a group of team and anyone can access that account) and team guys are having private private discussion(audio, video, text and screen-sharing) can anyone help me as I am totally new to JITSI.

You mean, there will be one meeting where everyone can join, and there can be private meetings between users. This sounds like a regular deployment with multiple conferences. For that you can just directly use meet.jit.si or if you want more control over the branding and users and resources you can use jaas.8x8.vc.

If you want to start your own deployment, follow Self-Hosting Guide - Debian/Ubuntu server · Jitsi Meet Handbook and start from there and maybe start with the iframeAPI and modify it to your needs … when you are comfortable with the system then you may start looking at the lib-jitsi-meet and doing a custom client, which is a lot of work, such client is jitsi-meet you can check the amount of code GitHub - jitsi/jitsi-meet: Jitsi Meet - Secure, Simple and Scalable Video Conferences that you use as a standalone app or embed in your web application..