for-in 语句 [英] for-in statement

问题描述

TypeScript 文档没有提到像 for 或 for-in 这样的循环.从使用语言来看，for 循环似乎只支持 any 或 string 变量.

TypeScript docs say nothing about loop like for or for-in. From playing with the language it seems that only any or string variables are supported in for loop.

为什么做出这个决定?

为什么不使用类型信息并具有强类型迭代变量?

Why not use the type information and have strongly-typed iteration variable?

推荐答案

for-in 语句确实用于枚举对象属性，这就是它在 TypeScript 中的实现方式.在数组上使用它存在一些问题.

The for-in statement is really there to enumerate over object properties, which is how it is implemented in TypeScript. There are some issues with using it on arrays.

我不能代表 TypeScript 团队发言，但我相信这是在语言中实现的原因.

I can't speak on behalf of the TypeScript team, but I believe this is the reason for the implementation in the language.

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