ESBuild with TypeScript
In this page:
require("esbuild").build({
entryPoints: ["src/index.ts"],
bundle: true,
outfile: "dist/bundle.js",
});Core Concept
esbuild is a bundler and transpiler written in Go that compiles TypeScript to JavaScript extremely fast by stripping types without performing any type checking itself — speed comes from that explicit tradeoff.
Example: Core Concept
// esbuild strips TypeScript types without checking them -- that's the speed tradeoff
console.log("esbuild transpiles fast by skipping type checking entirely");Basic Setup
A minimal setup calls esbuild.build({ entryPoints: ['src/index.ts'], bundle: true, outfile: 'dist/bundle.js' }) from a small Node script or the esbuild CLI directly, with no loader configuration needed for .ts files.
Example: Basic Setup
// esbuild.build({ entryPoints: ["src/index.ts"], bundle: true, outfile: "dist/bundle.js" });
console.log("No loader config needed -- esbuild handles .ts natively");Typed Example
Since esbuild only strips types and never checks them, a typed example still needs a parallel tsc --noEmit run (often in a separate terminal or CI step) to actually catch type errors during development.
Example: Typed Example
// esbuild alone won't catch type errors -- pair with:
// tsc --noEmit
console.log("A parallel tsc --noEmit run is required for real type safety");Project Usage
In a real project, esbuild is commonly used as the fast transform step inside a larger toolchain (Vite uses it this way) rather than as the sole build tool, precisely because it trades type safety for raw speed.
Example: Project Usage
// Vite itself uses esbuild internally as its fast dev transform step
console.log("esbuild is often one part of a larger toolchain, not standalone");Best Practices
Never rely on esbuild alone for type safety — always pair it with tsc --noEmit in CI, since a project can build and run successfully through esbuild even with real type errors present in the source.
Example: Best Practices
// package.json: "typecheck": "tsc --noEmit" (run in CI)
console.log("Never rely on esbuild alone for type safety -- always pair with tsc");- Expecting esbuild to report type errors, when it only strips types and never checks them.
- Relying on
emitDecoratorMetadata, which esbuild does not support. - Using
const enumacross files, since esbuild treats each file separately.
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