Passing a function as a prop to a Typescript React Functional Component

Question

I have a functional component (written in Typescript) that needs to pass a handler function down to a child component. Here is a scaled down version of the parent function:

type Props = { handleLocationChange(): void };

const Sidebar: React.FC<Props> = (props) => { 
 const handleLocationChange = () => {
    console.log('Location Changed.');
  };
return (
   <>
      <Search handleLocationChange={handleLocationChange} /> 
   </>
)
}

In VS Code the search component shows an error:

Type '{ handleLocationChange: () => void; }' is not assignable to type 'IntrinsicAttributes & { children?: ReactNode; }'. Property 'handleLocationChange' does not exist on type 'IntrinsicAttributes & { children?: ReactNode; }'.ts(2322)

Any help would be much appreciated. I am sure I am missing something small.

Answer 1

You need to declare the prop type in Search Component and declare type to parameter too:

//use this type to both components (children and parent)
interface FuncProps {
    //here you can declare the return type (here is void)
    handleLocationChange: (values: any) => void;
}
//children start
// here are the tip, define the type in the React.FC and in the FC's parameters itself
const Search: React.FC<FuncProps> = (props: FuncProps) => {
    ... your component behavior and view ...
    return (
        {/*↓↓↓↓ use the prop like this ↓↓↓↓*/}
        <input onClick={props.handleLocationChange('something if you need')}/>
    )
};
//children end

// parent start
const Sidebar: React.FC<Props> = (props: FuncProps) => { 
return (
   <>
      <Search handleLocationChange={props.handleLocationChange} /> 
   </>
)
}
//parent end

I hope this answer can help who wants to use typescript and want to easy your own life passing functions through components (I don't recomend pass functions through many levels).

Answer 2

You need to declare handleLocationChange as a prop on the Search component