如何在TypeScript中声明仅包含对象而不包含函数的类型 [英] How to declare a type in TypeScript that only includes objects and not functions

问题描述

在TypeScript中是否可以通过某种方式定义类型，使其仅包含对象但不包含函数?

Is it in TypeScript somehow possible to define a type so that it only includes objects but not functions?

示例:

type T = { [name: string]: any } // How to modify this to only accepts objects???

const t: T = () => {} // <- This should not work after modification

感谢您的帮助.

推荐答案

没有完美的方法来引用诸如不是函数的对象"之类的类型，因为这将需要真实的

There's no perfect way to refer to a type like "an object which is not a function", since that would require true subtraction types, and that doesn't exist in TypeScript (as of 3.1 at least).

一个简单的解决方法是查看 Function接口，并描述肯定不是 和Function的东西，但它会匹配您可能会遇到的大多数非功能对象.示例:

One easy-enough workaround is to look at the Function interface and describe something which is definitely not a Function, but which would match most non-function objects you're likely to run into. Example:

type NotAFunction = { [k: string]: unknown } & ({ bind?: never } | { call?: never });

这意味着具有一些未指定键的对象，该对象缺少bind属性或call属性".让我们看看它的行为:

That means "an object with some unspecified keys, which is either missing a bind property or a call property". Let's see how it behaves:

const okayObject: NotAFunction = { a: "hey", b: 2, c: true };
const notOkayObject: NotAFunction = () => {}; // error, call is not undefined

好.

这是一种解决方法，而不是简单的解决方案，其原因是某些非功能可能同时具有call和bind属性，并且您会遇到不希望出现的错误:

The reason that this is a workaround and not a straightforward solution is that some non-functions might have both a call and a bind property, just by coincidence, and you'll get an undesirable error:

const surprisinglyNotOkay: NotAFunction = { 
  publication: "magazine", 
  bind: "staples",
  call: "867-5309",
  fax: null
}; // error, call is not undefined

如果您确实需要支持此类对象，则可以将NotAFunction更改为更复杂，并排除更少的非功能，但是可能总会出现定义错误的情况.由您决定您想走多远.

If you really need to support such objects you can change NotAFunction to be more complicated and exclude fewer non-functions, but there will likely always be something the definition gets wrong. It's up to you how far you want to go.

希望有帮助.祝你好运！

Hope that helps. Good luck!

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