Since NPM v7.x, you can use the peerDependenciesMeta package.json config, which allows exactly that option. For example, in your “Module A” package.json: “peerDependencies”: { “winston”: “> 1.0.0 <= 1.2.10”, “foo”: “~2.3.0” }, “peerDependenciesMeta”: { “winston”: { “optional”: true } } In this case, when installing Module A as a dependency of another project, it will … Read more
I had this problem last night while migrating to Yarn v2 and using PnP. Make sure that after running yarn dlx @yarnpkg/sdks vscode the following folder structure was created inside your .yarn directory: .yarn/sdks/typescript/lib. Change your VSCode workspace configuration to add the following: “typescript.tsdk”: “.yarn/sdks/typescript/lib” I also had another problem with step 1 while using … Read more
[string] denotes a tuple with exactly one string element. Tuples are ordered lists of items, finite and usually fixed sized. string[] denotes an array of strings. Arrays will have variable size, including even a size of zero. The correct usage of the Tuple in your case would be: let type2:WithStringArray2 = { property: [‘someString’] }; … Read more
As of TypeScript 4.1, you can use a template literal type for this. type StartsWithPrefix = `prefix${string}`; This works for type unions as well: // `abc${string}` | `def${string}` type UnionExample = `${‘abc’ | ‘def’}${string}`; // For your example: type MyPrefixTypes = `${MyStringTypes}${string}`; const ok: UnionExample=”abc123″; const alsoOk: UnionExample=”def123″; const notOk: UnionExample=”abdxyz”; // Note that a … Read more
Create a helper type: type Overwrite<T, U> = Pick<T, Exclude<keyof T, keyof U>> & U; Usage: type HexColorLine = Overwrite<Line, { color: number }>
What about: class Destructed { private prefix: string; private suffix: string; constructor(opts: DestructedOptions) { Object.assign(this, opts); } } Also, there’s an open issue on this: Combining destructuring with parameter properties Edit If you want to avoid re-writing the properties in the class then you’ll need to make the members public, when that’s the case then … Read more
I managed to make the error go away while still being able to compute the type properly with the usage of @ts-ignore. An example can be found in the playground, in a nutshell if you remove the // @ts-ignore, in a full-fledged development environment, line I imagine that the code would not compile.
i’m using same configuration like yours but it only work when i downgrade to ts-node@9, and then i tried this option in my .mocharc.json and now it’s working as i expected { “extensions”: [“ts”], “spec”: [“**/*.spec.*”], “node-option”: [ “experimental-specifier-resolution=node”, “loader=ts-node/esm” ] }
This issue was raised in microsoft/TypeScript#36987. The authoritative (but not particularly informative) answer there is that this behavior is as intended, and required for backward compatibility. Generally speaking TypeScript doesn’t introduce breaking changes unless these changes improve many more things than they break. When the –noImplicitAny compiler option and the –strictNullChecks compiler option are both … Read more
Unlike classes, interfaces exist only at compile-time, they are not included into the resulting JavaScript, so you cannot do an instanceof check. You could make IWalkingAnimal a subclass of Animal (and use instanceof), or you could check if the object in question has a walk method: if (animal[‘walk’]) {} You can wrap this in a … Read more