属性 'map' 在类型 '() => IterableIterator 上不存在<number> '</number>

Question

I'm trying to pass keys as a React prop:

import * as React from "react";
import { render } from "react-dom";

const keys: string[] = ["a", "b"];

function App({keys}: string[]) {
  return (
    <div>
      {keys.map((key: string) => (
        <li>{key}</li>
      ))}
    </div>
  );
}

const rootElement = document.getElementById("root");
render(<App keys={keys} />, rootElement);

However, I get these errors:

Property 'map' does not exist on type '() => IterableIterator'.

Type 'string[]' is not assignable to type '() => IterableIterator'.

Why is this, and how to fix it?

Live code: https://codesandbox.io/s/changing-props-on-react-root-component-forked-9lj9ye?file=/src/index.tsx:0-341

Answer 1

You're typing your whole props as string[] instead of just keys . Embed keys prop in an object:

function App({ keys }: { keys: string[]; }) {
  // ...

Or using an interface:

interface AppProps {
  keys: string[];
}

function App({ keys }: AppProps) {
  // ...

Or a type:

type AppProps {
  keys: string[];
}

function App({ keys }: AppProps) {
  // ...

To go further: Differences Between Type Aliases and Interfaces