How to use Props with Generics with React.memo

Question

I am trying to convert the following to use React.memo:

interface Props {
  // props...
}

export function Table({
          


        

Answer 1

Don't you need to pass a component as the first parameter of React.memo? I couldn't test it, but I feel like this is the thought process:

// Overall format:
export const Table = memo(MyComponent, MyFunction)

// With empty arrow function:
export const Table = memo(MyComponent, () => {})

// With your code:
export const Table = memo(MyComponent, ({propA, propB}: Props<TRowData>) => {

})

Answer 2

I solved it by keeping it as a function, renaming the function to TableComponent and doing:

export const Table = memo(TableComponent) as typeof TableComponent

Answer 3

Simple, just pass a non-arrow function to React.memo:

export const Table = React.memo(function<T>(props: Props<T>) {

})

or if you need default export:

export default React.memo(function Table<T>(props: Props<T>) {

})

Answer 4

With current React type declarations, it is not possible to create a generic component out of React.memo. A solution without type assertions is to add an additional memo function overload to leverage TS 3.4 higher order function type inference:

import React, { memo } from "react"

declare module "react" { // augment React types
  function memo<A, B>(Component: (props: A) => B): (props: A) => ReactElement | null
  // return type is same as ReturnType<ExoticComponent<any>>
}

You then will be able to make Table component generic. Just make sure to pass a generic function to memo:

interface Props<T> {
  a: T
}

const TableWrapped = <T extends {}>(props: Props<T>) => <div>{props.a}</div>

const Table = memo(TableWrapped)

const App = () => (
  <>
    <Table a="foo" /> {/* (props: Props<string>) => ... */}
    <Table a={3} /> {/* (props: Props<number>) => ... */}
  </>
)

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