Starting with the DataTable 📊⚡

As part of our HFT trading senior design project, I’ve been building out the GUI. One of the first reusable components we needed was a DataTable. This table will be central for multiple panels: the blotter (our orders and fills), the top-of-book snapshot (market data), and eventually the order book ladder.

I’ve had concerns about React being a bottleneck compared to low-level approaches (FPGA, C++), but for the GUI layer, React is fine as long as rendering stays predictable. The real compute happens on the backend. My focus for the front-end is speed, clarity, and an HFT-style look.

Why a Generic Table?

The component is generic over a row type. Each column definition uses a key from that row type. This enforces compile-time safety: if I define a column for "price" but the row doesn’t have that field, the build fails.

Why this matters: In trading systems, schemas change constantly. Catching mismatches at compile time prevents “undefined” cells during critical sessions.

Why Require a Stable id?

Every row must have an id. React uses that as a stable key when reconciling DOM updates.

In a blotter where new rows constantly stream in at the top, index-based keys make React think the entire table changed on every insert. That causes wasteful re-renders and visible jank. A stable id keeps updates localized.

Why This Column Model?

The column definition is minimal: just header, optional width, and alignment.

• Width ensures consistent layouts — timestamps can be fixed-width, prices can stay aligned in neat columns.
• Alignment reduces cognitive load — traders expect prices and quantities to be right-aligned, which makes scanning for changes faster.

This is lean on purpose: an MVP doesn’t need sorting or filtering built in.

Why a Fixed Header + Scrollable Body?

The header is fixed while the body scrolls. Traders rely on labels always being visible while scanning deep lists. By scoping scroll to the body only, the overall page remains locked, which is critical when docking multiple panels side-by-side.

Why Use <div>s Instead of <table>?

Using <div>s with flexbox instead of semantic <table> markup is a pragmatic choice:

• Easier to style consistently in dark themes.
• Easier to virtualize later when rendering thousands of rows.
• Easier to animate, e.g. flashing cells green/red on updates.

Native tables are rigid once you need sticky headers, depth bars, or animations. Divs keep me in full control.

Why Cast to String and Add Tooltips?

Each cell explicitly casts its value to a string. That guarantees consistent rendering regardless of the underlying type. I also added a tooltip (title) for truncated values, balancing density with accessibility.

Why Control Height Through Props and CSS?

Inline height is only applied if explicitly passed as a prop. Otherwise, CSS dictates layout. This avoids the “inline style wins” trap, keeping the component flexible — it can fill 100% height or 50% width depending on its container.

Why Keep It Stateless?

The table does not handle sorting, filtering, or selection. That’s intentional: for HFT GUIs, the DataTable should be a dumb fast renderer. Higher-level logic belongs outside. This makes it predictable and prevents heavy computations from blocking paints.

Trade-offs and Future Work

• Virtualization for very large lists.
• Change flashes to highlight updates.
• Memory optimization if GC pressure grows.
• Accessibility improvements with ARIA roles while keeping div flexibility.

Takeaway ✨

This DataTable is small, type-safe, and layout-predictable — exactly what’s needed for an MVP HFT trading UI. It’s fast, easy to reason about, and leaves room for performance optimizations when real feeds come online.

Going forward, I’ll layer in virtualization, coalesced paints, and maybe even Canvas for hotspots. For now, this gives us a solid foundation for building the rest of the trading interface.