CLI

WASM Tooling — A Practical Cheat Sheet

The WebAssembly ecosystem has accumulated a solid set of command-line tools that don’t get surfaced well in most introductory material. Tutorials tend to focus on one language path — Rust via wasm-pack, or Go, or Emscripten — and leave the broader toolchain unexplained. This is a reference for the tools I reach for regularly: inspection, compilation, optimisation, and runtimes.

The Text Format — WAT

Before the tools: WASM has two representations. The binary format (.wasm) is what the runtime executes. The text format (.wat) is human-readable S-expression syntax — the assembly language of WebAssembly. Understanding WAT is useful for debugging and for writing minimal WASM by hand.

Simulating Colour Blindness with ImageMagick

Colour blindness affects roughly 8% of men and 0.5% of women with Northern European ancestry. For a data visualisation that uses colour as the primary encoding — a choropleth, a multi-series line chart, a heatmap — that’s a meaningful share of the audience for whom the visual may be conveying the wrong information, or none at all.

The right time to test this is during design, not after a complaint. ImageMagick’s -color-matrix flag lets you simulate the major forms of colour vision deficiency directly on any image — screenshots, design exports, chart renders — from the command line. This makes it scriptable, batchable, and easy to drop into a CI pipeline alongside screenshot tests.