Best way to build a JavaScript-heavy client-side page for calculations and graphs?

Hey everyone,

I want to build a client-side web page that relies heavily on JavaScript. It will perform calculations and display graphs and bar charts based on those calculations.

The page will also need to make HTTP calls to an external site, all from the client side.

Here are the key requirements:

  1. User-friendly for CEOs – Clean and intuitive UI.
  2. Responsive design – Should look proportional on all screen sizes, including mobile and different browsers.
  3. Lightweight – Needs to be optimized for performance.

I'm a developer, so feel free to get technical—I want to understand the most efficient way to build this. The server-side logic will be minimal (about 98% of the work happens on the client side).

What technologies or frameworks would you recommend for this?