storybook-10-esm-only¶
Insight: Storybook 10 drops CommonJS support and ships ESM-only builds. This results in 15% smaller install sizes (could have been 50% but they chose to ship readable, unminified code instead). Requires Node.js 20.16+, 22.19+, or 24+. The transition was enabled by Node.js's require(esm) support, which allows CJS consumers to still require ESM packages.
Detail: Key practical implications for design system teams: (1) config and story files must be valid ESM, (2) most addons should continue working, (3) shipping unminified code means Storybook internals are now human-readable and auditable. This is part of the broader JavaScript ecosystem convergence on ESM. For design systems that distribute component libraries, this signals that tooling is moving decisively to ESM and teams should plan their module strategy accordingly. Storybook 10 is in beta with stable release planned weeks after the announcement.
Sources
- Storybook Blog — "Storybook is going ESM-only" (2025-09-22)
Related: existing entry "Storybook 9 beta" in external/design-systems.md — SUPERSEDES