Optimisation: memoize computations

[JobLeonard]

This can greatly improve the speed of plotters:

Memoization

Calling the same function over and over again is wasteful if we know that the function is pure. We can create a memoized version of a function that keeps track of the last argument and last result. That way we don't have to reexecute it if we keep using the same value.

function memoize(fn) {
  var cachedArg;
  var cachedResult;
  return function(arg) {
    if (cachedArg === arg) {
      return cachedResult;
    }
    cachedArg = arg;
    cachedResult = fn(arg);
    return cachedResult;
  };
}

var MemoizedNameBox = memoize(NameBox);

function NameAndAgeBox(user, currentTime) {
  return FancyBox([
    'Name: ',
    MemoizedNameBox(user.firstName + ' ' + user.lastName),
    'Age in milliseconds: ',
    currentTime - user.dateOfBirth
  ]);
}

https://github.com/reactjs/react-basic

[JobLeonard]

Implemented for scatterplot