Bundle Generated using esbuild throwing the exception

[hassanazharkhan]

I'm getting the following exception while running my bundled file on local, I'am using the library called dynamo-easy which is heavily relies on typescript decorators.

Exception:

throw new Error("make sure you have enabled the typescript compiler options which enable us to work with decorators (see doc)");

tsconfig.json:

{
  "extends": "../../tsconfig.build.json",
  "compilerOptions": {
    "rootDir": "./",
    "outDir": "./dist"
  },
  "include": [
    "./src/**/*"
  ]
}

tsconfig.build.json

{
  "compilerOptions": {
    "sourceMap": true,
    "target": "es2019",
    "esModuleInterop": true,
    "resolveJsonModule": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "importHelpers": true,
    "declaration": true,
    "module": "commonjs"
  },
  "exclude": [
    "node_modules",
    "dist",
    "build",
    "**/build",
    "**/dist",
    "**/node_modules",
    "cdk.out",
    "**/cdk.out",
    "__mocks__",
    "**/__mocks__/**",
    "**/__tests__/**",
    "**/*.test.ts"
  ]
}

esbuild version: ^0.12.25
Os: MacOS BigSur

[evanw]

Looks like TypeScript decorators are working fine to me:

$ cat foo/bar/tsconfig.json 
{
  "extends": "../../tsconfig.build.json",
  "compilerOptions": {
    "rootDir": "./",
    "outDir": "./dist"
  },
  "include": [
    "./src/**/*"
  ]
}

$ cat tsconfig.build.json 
{
  "compilerOptions": {
    "sourceMap": true,
    "target": "es2019",
    "esModuleInterop": true,
    "resolveJsonModule": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "importHelpers": true,
    "declaration": true,
    "module": "commonjs"
  },
  "exclude": [
    "node_modules",
    "dist",
    "build",
    "**/build",
    "**/dist",
    "**/node_modules",
    "cdk.out",
    "**/cdk.out",
    "__mocks__",
    "**/__mocks__/**",
    "**/__tests__/**",
    "**/*.test.ts"
  ]
}

$ cat foo/bar/check.ts 
let didDecoratorsWork = false
let decorator = () => didDecoratorsWork = true
@decorator class Foo {}
console.log({ didDecoratorsWork })

$ esbuild foo/bar/check.ts | node
{ didDecoratorsWork: true }

You'll have to be more specific about what isn't working. Right now I have no way of reproducing your issue.

[hassanazharkhan]

@evanw Thank you for looking into this, I have created a repo with the bug stated above, would you able to check there?

https://github.com/hassanazharkhan/esbuild-decorator-bug

Reproduction steps:

npx projen && node esbuild.js && node -e "console.log(require('./build/index.js').handler({}));"

[evanw]

It looks like this library you're trying to use relies on TypeScript's emitDecoratorMetadata setting. This does not work with esbuild because it requires a type system to function, and replicating TypeScript's type system within esbuild is out of scope due to complexity. One workaround is to run tsc first to convert .ts files into .js files and then run esbuild on the resulting .js files. But your issue is not a problem with esbuild because emitDecoratorMetadata is intentionally not supported.