Any difference between type assertions and the newer `as` operator in TypeScript?
From Wiki page: "What's new in TypeScript [1.6]":
New
.tsx
file extension andas
operatorTypeScript 1.6 introduces a new
.tsx
file extension. This extension does two things: it enables JSX inside of TypeScript files, and it makes the newas
operator the default way to cast (removing any ambiguity between JSX expressions and the TypeScript prefix cast operator). For example:var x = <any> foo; // is equivalent to: var x = foo as any;
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.