FAQ

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Daniel Rosenwasser edited this page Dec 9, 2015 · 7 revisions

Why are function parameters are bivariant?

Why are functions with fewer parameters assignable to functions that take more parameters?

Why are functions returning non-`void` assignable to function returning `void`?

Why are all types are assignable to empty interfaces?

Why is `A<string>` assignable to `A<number>` for `interface A<T> { }`?

Why aren't classes nominal?

Why are enums nominal?

Why does `this` get orphaned on my instance methods?

Why is my output file empty when I use module exports with `--outFile`?

Decorators on function declarations

Why are getters without setters not considered read-only?

I wrote `declare var MyComponent: React.Component;`, why can't I write `<MyComponent />`

Why don't namespaces merge across different module files?

What's the difference between `enum` and `const enum`s?

What's the difference between `declare class` and `inteface`?

Can I make a type alias nominal?

How do I prevent two types from being structurally compatible?

What does it mean for an interface to extend a class?

Why am I getting an error about a missing index signature?

Why can't I use `x` in `function f({ x: number }) { /* ... */ }`?

Why don't I get type checking for `(number) => string`?

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