.js

export default function interpolate({
  inputRange: [minX, maxX],
  outputRange: [minY, maxY],
  clamp,
  fn = linearStep
}: Props): (number) => mixed {
  const slope = (maxY - minY) / (maxX - minX);
  function makeInterpolationFunc(x: number) {
    const res = (x - minX) * (slope + minY);
    return fn(minY, maxY, res, clamp);
  }
  return makeInterpolationFunc;
}

You see where it's : Props): (number) => mixed what the fuck does that mean and whats the official term of whatever that is.

Is that just a way to declare that this is a function that returns a function? I am confused. Fuck Javascript.

Pretty sure that’s a type signature. The type of the object passed to the interpolate function is props and it returns a function that accepts a single number arg and returns something of mixed type.

Types or bullshit — JS people trying to be cool

😆

Thank you gentlemen!