53 lines
2.0 KiB
Markdown
53 lines
2.0 KiB
Markdown
# `tslib` direct dependency migration
|
|
|
|
## What does this migration do?
|
|
|
|
If you have any libraries within your workspace, this migration will convert `tslib` peer dependencies to direct dependencies for the libraries.
|
|
TypeScript uses the `tslib` package to provide common helper functions used in compiled TypeScript code.
|
|
The `tslib` version is also updated to `2.0.0` to support TypeScript 3.9.
|
|
|
|
Before:
|
|
```json
|
|
{
|
|
"name": "my-lib",
|
|
"version": "0.0.1",
|
|
"peerDependencies": {
|
|
"@angular/common": "^9.0.0",
|
|
"@angular/core": "^9.0.0",
|
|
"tslib": "^1.12.0"
|
|
}
|
|
}
|
|
```
|
|
|
|
After:
|
|
```json
|
|
{
|
|
"name": "my-lib",
|
|
"version": "0.0.1",
|
|
"peerDependencies": {
|
|
"@angular/common": "^9.0.0",
|
|
"@angular/core": "^9.0.0"
|
|
},
|
|
"dependencies": {
|
|
"tslib": "^2.0.0"
|
|
}
|
|
}
|
|
```
|
|
|
|
## Why is this migration necessary?
|
|
|
|
The [`tslib`](https://github.com/Microsoft/tslib) is a runtime library for Typescript.
|
|
The version of this library is bound to the version of the TypeScript compiler used to compile a library.
|
|
Peer dependencies do not accurately represent this relationship between the runtime and the compiler.
|
|
If `tslib` remained declared as a library peer dependency, it would be possible for some Angular workspaces to get into a state where the workspace could not satisfy `tslib` peer dependency requirements for multiple libraries, resulting in build-time or run-time errors.
|
|
|
|
As of TypeScript 3.9 (used by Angular v10), `tslib` version of 2.x is required to build new applications.
|
|
However, older libraries built with previous version of TypeScript and already published to npm might need `tslib` 1.x.
|
|
This migration makes it possible for code depending on incompatible versions of the `tslib` runtime library to remain interoperable.
|
|
|
|
|
|
## Do I still need `tslib` as a dependency in my workspace `package.json`?
|
|
|
|
Yes.
|
|
The `tslib` dependency declared in the `package.json` file of the workspace is used to build applications within this workspace, as well as run unit tests for workspace libraries, and is required.
|