打字稿类型转换不起作用 [英] Typescript type casting not working
问题描述
我对TypeScript很陌生。我从一本名为《 Typescript Revealed》(2013年2月出版)开始。在第二章中,有一个名为 Casts的部分,具有以下示例:
I am pretty new to TypeScript. I started with a book called Typescript Revealed (Pub Feb.2013). In Chapter 2 there is a section called "Casts" that has the following example:
var a:int =< int> SomeNumberAsAString;
我尝试应用以下示例:
var SomeNumberAsAString = "1000";
var a: int = <int>SomeNumberAsAString;
但是编译器给了我一个错误:
But compiler gave me an error:
hello.ts(2,8):错误TS2304:找不到名称'int'。
hello.ts(2,15):错误TS2304:找不到名称' int'。
hello.ts(2,8): error TS2304: Cannot find name 'int'.
hello.ts(2,15): error TS2304: Cannot find name 'int'.
我想知道如何进行此类型转换,或者Typescript的规范已更改?
I'm wondering how to do this cast, or has the specification of Typescript changed?
推荐答案
(2013年2月发布)
(Pub Feb.2013)
那本书是旧。现在称为 number
。
That book is old. Its called number
now.
var SomeNumberAsAString = "1000";
var a: number = <number><any>SomeNumberAsAString;
此外,此断言是非常不安全的,我不会在生产代码中这样做。但这很重要:)
Also this assertion is very unsafe and I would not do this in production code. But it gets the point across :)
有关断言的最新书籍章节:< a href = https://basarat.gitbooks.io/typescript/content/docs/types/type-assertion.html> https://basarat.gitbooks.io/typescript/content/docs/types/type-assertion .html
A more up to date book chapter on assertions : https://basarat.gitbooks.io/typescript/content/docs/types/type-assertion.html
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