withProps HOC. For when you want to inject arbitrary stuff into a component

withProps.tsx

import * as React from 'react';

export default function withProps<InjectProps, Props = {}>(Component: React.ComponentType<Props & InjectProps>, props: InjectProps): React.ComponentClass<Pick<Props, Exclude<keyof Props, keyof InjectProps>>> {
  return class extends React.Component<Props> {
    static displayName = `withProps(${Component.displayName || Component.name})`;
    static WrappedComponent = Component;
    render() {
      return <Component {...this.props} {...props} />
    }
  }
}


// test it out...
  
interface InjectedProps { a: number }
interface OwnProps { b: string }
const Test = (props: OwnProps & InjectedProps) => (<p>{props.a} {props.b}</p>)

let InjectedTest = withProps<InjectedProps, OwnProps>(Test, { a: 123 })

class Test2 extends React.Component {
  render() {
    return (
      <>
        <Test a={123} b="asd" />
        <InjectedTest b="abc" />
      </>
    );
  }
}