类型断言与TypeScript中较新的`as`运算符之间有何区别？ [英] Any difference between type assertions and the newer `as` operator in TypeScript?

问题描述

TypeScript规范称为类型断言之间是否有任何区别：

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

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

和更新 as 运算符：

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

两者通常都用于编译时转换吗？

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

推荐答案

区别在于 Circle 在TSX文件中有效，而< Circle> ; 与JSX语法冲突。出于这个原因引入了 as 。

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

例如，中的以下代码。 tsx 文件：

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

将导致以下错误：

错误TS17002：预期'Circle'对应的JSX结束标记。

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

但是，作为Circle 可以正常工作。

从现在开始使用作为Circle 。这是推荐语法。

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

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