casting - Any difference between type assertions and the newer `as` operator in TypeScript?

Question

Is there any difference between what the TypeScript spec calls a type assertion:

var circle = <Circle> createShape("circle");

And the newer as operator:

var circle = createShape("circle") as Circle;

Both of which are typically used for compile-time casting?

Answer 1

The difference is that as Circle works in TSX files, but <Circle> conflicts with JSX syntax. as was introduced for this reason.

For example, the following code in a .tsx file:

var circle = <Circle> createShape("circle");

Will result in the following error:

error TS17002: Expected corresponding JSX closing tag for 'Circle'.

However, as Circle will work just fine.

Use as Circle from now on. It's the recommended syntax.