swyxio

// create context with no upfront defaultValue
// without having to do undefined check all the time
function createCtx<A>() {
  const ctx = React.createContext<A | undefined>(undefined)
  function useCtx() {
    const c = React.useContext(ctx)
    if (!c) throw new Error("useCtx must be inside a Provider with a value")
    return c
  }
  return [useCtx, ctx.Provider] as const

gaearon

class Spiderman {
  lookOut() {
    alert('My Spider-Sense is tingling.');
  }
}

let miles = new Spiderman();
miles.lookOut();