如何在 TypeScript 中键入这个“as”JSX 属性？

Question

我正在描述一个 React 库，它通过名为 as 的属性获取组件或 HTML 标记名称。当给定as 属性时，它会根据该组件/标签名称创建一个元素，并传递任何其他给定属性。

这里有一些例子：

<Foo as="a" href="https://example.com" />
<Foo as={FancyButton} fancyButtonAttr="hello!" />

我知道Semantic UI does something similar with augmentations。我将如何在 TypeScript 中输入这个？

Answer 1

我将举例说明此处给出的最基本要求。你可以尝试泛化到一些更复杂的东西。

首先，这是我们的魔法组件！

import * as React from "react";

function Foo<Tag extends AnyTag>(props: { as: Tag } & PropsOf<Tag>): JSX.Element;

注意两点：

• 一种叫做AnyTag的类型
• 称为PropsOf 的实用程序类型

那是我们的公开签名。我们也许可以使用该签名以类型安全的方式实现这一点，但我们可以在实现签名中“作弊”。这取决于您作为实施者。

function Foo(props: any) {
    return <div>Implementation goes here!</div>
}

让我们回到我们提到的那两种类型。 AnyTag 是 JSX 标签可以是的任何东西。

type AnyTag = string
            | React.FunctionComponent<never>
            | (new (props: never) => React.Component);

PropsOf 尝试获取给定 HTML 标记名称或组件的预期属性。

type PropsOf<Tag> =
    Tag extends keyof JSX.IntrinsicElements ? JSX.IntrinsicElements[Tag] :
    Tag extends React.ComponentType<infer Props> ? Props & JSX.IntrinsicAttributes :
    never
;

现在让我们定义几个采用相同 props 的组件 - 一个函数和一个类。

interface SomeProps {
  x: boolean; y: boolean; z: boolean;
}

function Bar(props: SomeProps) {
    return <div>{props.x} {props.y} {props.z}</div>;
}

class Baz extends React.Component<SomeProps> {
    render() {
        const { x, y, z } = this.props;
        return <div>{x} {y} {z}</div>;
    }
}

下面是一些用法！

let a1 = <Foo as="a" href="https://kthxb.ai" />;         // good!
let a2 = <Foo as="div" href="https://kthxb.ai" />;       // error!
let a3 = <Foo as="a" href={100} />;                      // error!

let b1 = <Foo as={Bar} x y z />;                         // good!
let b2 = <Foo as={Bar} x y z asdsadsada />;              // error!
let b3 = <Foo as={Bar} x={1} y={2} z={3} asdsadsada />;  // error!

let c1 = <Foo as={Baz} x y z />;                         // good!
let c2 = <Foo as={Baz} x y z asdsadsada />;              // error!
let c3 = <Foo as={Baz} x={1} y={2} z={3} asdsadsada />;  // error!

一共

import * as React from "react";

// Here's our magic component!
// Note two things:
//   - A type called AnyTag
//   - A utility type called PropsOf
function Foo<Tag extends AnyTag>(props: { as: Tag } & PropsOf<Tag>): JSX.Element;

// That was our public signature. We might be able to implement this in a type-safe way using that signature,
// but we can "cheat" a little here in the implementation signature. This is up to you as the implementer.
function Foo(props: any) {
    return <div>Implementation goes here!</div>
}

// AnyTag is anything that a JSX tag can be.
type AnyTag = string
            | React.FunctionComponent<never>
            | (new (props: never) => React.Component);

// PropsOf tries to get the expected properties for a given HTML tag name or component.
type PropsOf<Tag> =
    Tag extends keyof JSX.IntrinsicElements ? JSX.IntrinsicElements[Tag] :
    Tag extends React.ComponentType<infer Props> ? Props & JSX.IntrinsicAttributes :
    never
;

// Let's now define a few components taking the same props - one function and one class.

interface SomeProps {
  x: boolean; y: boolean; z: boolean;
}

function Bar(props: SomeProps) {
    return <div>{props.x} {props.y} {props.z}</div>;
}

class Baz extends React.Component<SomeProps> {
    render() {
        const { x, y, z } = this.props;
        return <div>{x} {y} {z}</div>;
    }
}

// Now here's some usage!

let a1 = <Foo as="a" href="https://kthxb.ai" />;         // good!
let a2 = <Foo as="div" href="https://kthxb.ai" />;       // error!
let a3 = <Foo as="a" href={100} />;                      // error!

let b1 = <Foo as={Bar} x y z />;                         // good!
let b2 = <Foo as={Bar} x y z asdsadsada />;              // error!
let b3 = <Foo as={Bar} x={1} y={2} z={3} asdsadsada />;  // error!

let c1 = <Foo as={Baz} x y z />;                         // good!
let c2 = <Foo as={Baz} x y z asdsadsada />;              // error!
let c3 = <Foo as={Baz} x={1} y={2} z={3} asdsadsada />;  // error!