This is a "bare minimum" repo that shows one way to configure TypeScript Project References with lerna. There are a lot of different ways you can set things up and this isn't intended to be authoratitive guidance or exclusionary of other ways that might work better in your project.
> git clone https://github.com/RyanCavanaugh/learn-a.git
> cd learn-a
> npm install
> lerna bootstrap
> tsc -b packages
Note that you'll need a 3.0 version of tsc
(currently available at npm install -g typescript@next
).
As with a normal lerna repo, there's a packages
folder. Inside we have three creatively named packages pkg1
, pkg2
, and pkg3
.
packages/
| tsconfig.settings.json
| tsconfig.json
| pkg1/
| tsconfig.json
| src/
| | (typescript files)
| lib/
| | (javascript files)
| | (.d.ts files)
| pkg2/
| (same as pkg1)
| pkg3/
| (same as pkg1)
Let's review each file in the repo and explain what's going on
{
"compilerOptions": {
// Always include these settings
"composite": true,
"declaration": true,
"declarationMap": true,
"sourceMap": true,
// These settings are totally up to you
"esModuleInterop": true,
"target": "es5",
"module": "commonjs",
"strict": true
}
}
This file contains the "default" settings that all packages will use for compilation. You will definitely want the composite
, declaration
, declarationMap
, and sourceMap
settings enabled for all projects, so include those in this file. Other settings, like target
and strict
, can be specified here if you'd like to enable them by default. You'll also be able to override these settings on a per-package basis if needed.
{
"files": [],
"references": [
{ "path": "pkg1" },
{ "path": "pkg2" },
{ "path": "pkg3" }
]
}
This file is pretty simple - simply list the packages that need to be built with tsc
in the references
array.
You should also include "files": []
in this file - this will prevent an incorrect invocation of tsc
without -b
from trying to build the entire packages folder source files as one compilation (which will fail, but drop a bunch of .js files in random places as an annoying side effect).
We'll just cover one of the pkg1
/ pkg2
/ pkg3
packages since they're basically identical for the purposes of this demo. Here's pkg2
's tsconfig.json
:
{
"extends": "../tsconfig.settings.json",
"compilerOptions": {
"outDir": "lib",
"rootDir": "src"
},
"references": [
{ "path": "../pkg1" }
]
}
The extends
property pulls in the settings we wrote in tsconfig.settings.json
, so we don't have to duplicate any settings described there.
In compilerOptions
, we've set outDir
to lib
and rootDir
to src
, then placed all my .ts
files in src
. This means src/index.ts
will build to lib/index.js
and lib/index.d.ts
. This is also the place where you could override settings like strict
or target
if you needed to change them on a per-project basis.
In the references
array, we list the paths to the other projects' tsconfig.json
files (or containing folders, as shown here). This will both ensure that we locate the .d.ts
files correctly, and set up a proper build ordering.
import * as p1 from '@ryancavanaugh/pkg1';
export function fn4() {
p1.fn();
}
Nothing unusual going on here. We import and export with the usual syntax. Notably, if you open this repo in an editor, you can still "Go to Definition (F12)" on p1.fn
here and land in pkg1/foo.ts
- the original sourcecode - even though "under the covers" it's using the much faster .d.ts
file for typechecking.
Here are the relevant excerpts from the package.json
:
{
"main": "lib/index.js",
"typings": "lib/index.d.ts",
"scripts": {
"prepublishOnly": "tsc -b ."
},
"devDependencies": {
"typescript": "^3.0.0-dev.20180626"
}
}
Because we build to lib
, we need to set main
to the .js
file there and typings
to the .d.ts
file.
In scripts
, we use the local copy of tsc
(listed here as a dev dependency) to run a build mode compilation on the project. This will ensure that the lib
folder is always built before npm publish
, and blocks any publishes that try to push non-compiling code.
.gitignore
lib/
.npmignore
# Empty, but needs to exist
The .gitignore
stops us from checking in build outputs, which is generally a good idea. By default, npm
won't publish files that are ignored by git
, so we need a separate .npmignore
file so that the lib
folder still gets published!
All your lerna commands and workflow will work as expected here.
To build the TypeScript projects, you can run individual builds with tsc -b
:
> tsc -b packages/pkg3
Or just build everything:
> tsc -b packages