Gulp sourcemaps with TypeScript and Babel

Question

I am currently writing a side project where I can learn more about TypeScript and ES6 (using babel).

I wanted to use ES6 with my TypeScript, so I settled on the following workflow.

Typescript (ES6) -> Babel (ES6) -> ES5

Now I am using Gulp to automate all of this, and I am having a hard time getting the sourcemaps to generate properly. I should mention that this style was suggested to me by a user on /r/typescript so I am not even sure if it is possible.

Anyways here is my current gulp task

var server = $.typescript.createProject('src/server/tsconfig.json');
gulp.task('build', ['vet'], function () {
  var sourceRoot = path.join(__dirname, 'src/server/**/*.ts');
  return gulp.src('src/server/**/*.ts')
    .pipe($.sourcemaps.init())
      .pipe($.typescript(server))
      .pipe($.babel())
    .pipe($.sourcemaps.write('.', { sourceRoot: sourceRoot}))
    .pipe(gulp.dest('build/server'));
});

I have tried many different approaches, but none work. When debugging in VSCode, the entrypoint of my app: build/server/index.js loads and finds the source file src/server/index.ts properly.

However when VSCode attempts to step into another file say build/server/utils/logger/index.js it looks for src/server/utils/logger/index.js which it doesn't find because it should be looking for a *.ts file.

So what am I doing wrong? Or is this even possible? I've been staring at this for about 5 hours now. So any insight would be great.

Also VSCode 0.9.x displays the '.../.js' file not found and VSCode 1.0 just fails silently.

my tsconfig.json, it gets passed in by $.typescript.createProject()

{
  "compilerOptions": {
    "module": "commonjs",
    "noImplicitAny": true,
    "removeComments": true,
    "preserveConstEnums": true,
    "target": "ES6",
    "sourceMap": true,
    "outDir": "build/server"
  }
}

.babelrc

{
  "presets": ["es2015"]
}

Here is the relevant npm packages

"devDependencies": {
    "babel-polyfill": "^6.2.0",
    "babel-preset-es2015": "^6.1.18",
    "gulp-babel": "^6.1.0",
    "gulp-sourcemaps": "^1.6.0",
    "gulp-typescript": "^2.9.2"
}

Edit: I have done some investigating into the gulp-sourcemaps, and when not using babel the sourcemaps work properly. (Removed all irrelevant info)

src/server/up/up2/four.ts - No Babel

{
  "history": [ "/home/user/code/test/src/server/up/up2/four.js" ],
  "base": "/home/user/code/test/src/server/",
  "sourceMap": {
    "sources": ["up/up2/four.ts"],
    "file": "up/up2/four.js"
  }
}

Notice how in sourceMap.sources it lists the proper source file up/up2/four.ts

Now here is an example when I add gulp-babel into the task.

src/server/up/up2/four.ts - With Babel

{
  "history": [ "/home/user/code/test/src/server/up/up2/four.js" ],
  "base": "/home/user/code/test/src/server/",
  "sourceMap": {
    "sources": ["four.js"],
    "file": "up/up2/four.js"
  },
  "babel": {
    "...": "..."
  }
}

Notice how the sourceMap.sources now incorrectly shows the four.js instead of the typescript file.

Curiously enough, as long as the typescript files are in the root directory src/server they build the source maps just fine.

src/server/two.ts - With Babel

{
  "history": [ "/home/user/code/test/src/server/two.js" ],
  "base": "/home/user/code/test/src/server/",
  "sourceMap": {
    "sources": ["two.ts"],
    "file": "two.js"
  },
  "babel": {
    "...": "..."
  }
}

Answer 1

Update

It appears that the specific issue in this question is related to Babel's incorrect source map generation for files which are not in the working directory. There is already an issue filed here.

For a vinyl File object like

new File({
  cwd: '.',
  base: './test/',
  path: './test/some/file.js'
  ...
});

the generated source map should have something like

{
  ...
  "sources": ["some/file.js"]
  ...
}

but gulp-babel gives

{
  ...
  "sources": ["file.js"]
  ...
}

This causes the Typescript source maps and Babel source maps to be incorrectly merged, but only when the file is deeper than the working directory.

While this issue is being resolved, I recommend targeting ES5 with Typescript and bypassing Babel completely. This produces correct source maps.

gulp.task('build', function () {
  return gulp.src('src/server/**/*.ts')
    .pipe(sourcemaps.init())
    .pipe(typescript({
      noImplicitAny: true,
      removeComments: true,
      preserveConstEnums: true,
      target: 'es5',
      module: 'commonjs'
    }))
    .pipe(sourcemaps.write('.', { sourceRoot: 'src/server' }))
    .pipe(gulp.dest('build/server'));
});

---

Previous Answer

You are close, but there are a couple mistakes I noticed in your configuration:

1. "module": "commonjs" is incompatible with "target": "es6". Output ES6 modules with Typescript and let Babel transpile them to CommonJS.
2. "outDir" is not necessary when using Gulp since you are working with a stream. Intermediate results (i.e. results of Typescript) are not written to disk at all.
3. "sourceMap": true is not necessary together with Gulp sourcemaps.

I have created a project which compiled for me, with babel@6.1.18 and typescript@1.6.2.

Directory structure

.
├── gulpfile.js
└── src
    └── server
        ├── one.ts
        └── two.ts

one.ts

export class One {};

two.ts

import { One } from './one';

export class Two extends One {}

gulpfile.js

I have inlined all configurations for terseness, but you should be able to use config files just as easily.

var gulp = require('gulp');

var sourcemaps = require('gulp-sourcemaps');
var typescript = require('gulp-typescript');
var babel = require('gulp-babel');

gulp.task('build', function () {
  return gulp.src('src/server/**/*.ts')
    .pipe(sourcemaps.init())
    .pipe(typescript({
      noImplicitAny: true,
      removeComments: true,
      preserveConstEnums: true,
      target: 'es6'
    }))
    .pipe(babel({
      presets: [ 'es2015' ]
    }))
    .pipe(sourcemaps.write('.', { sourceRoot: 'src/server' }))
    .pipe(gulp.dest('build/server'));
});