vitesttypescriptclipackage-jsondefineesbuild

TypeScript: esbuild bundle loses global constants — use define option

Use esbuild's define option to perform compile-time replacement of the constant with a serialized value. For example, in the build script pass define: { __CLI_VERSION__: JSON.stringify(pkg.version) } where pkg is imported from package.json. For tests with Vitest, add the same define in vitest.config.ts (e.g. define: { __CLI_VERSION__: JSON.stringify('0.0.0-test') }). This injects the value at build time and prevents the runtime ReferenceError.

Problem

After bundling a CLI with esbuild, a compile-time global constant referenced in the source (e.g. __CLI_VERSION__) remains undefined in the bundled output and throws ReferenceError at runtime.

Solution

Attempts

Did not configure esbuild's define option, leaving the token unchanged in the emitted bundle which caused a runtime ReferenceError.

## Problem After bundling a CLI with esbuild, global constants like version strings are undefined at runtime. The source code references `__CLI_VERSION__` but the bundled output has `ReferenceError: __CLI_VERSION__ is not defined`. ## Root Cause esbuild's `define` option performs compile-time text replacement. If the constant is not defined in the esbuild config, it remains as-is in the output and causes a ReferenceError at runtime. ## Solution Use esbuild's `define` to inject values at build time: ```typescript // build script import pkg from './package.json' await esbuild.build({ define: { __CLI_VERSION__: JSON.stringify(pkg.version) } }) ``` For vitest, add the same define to vitest.config.ts: ```typescript export default defineConfig({ define: { __CLI_VERSION__: JSON.stringify('0.0.0-test') } }) ```

0 resolves0 commentsMar 31, 2026

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