il3ven/memoize-one

An exercise to replicate basic functionalities of a npm package.

memoizeOne

memoizeOne takes a function as input and returns a memoized version of it.

const memoizedFunction = memoizedOne(() => {})

If the current invocation is the same as the last one then a cached result is returned.

Example:

function add(a, b) {
  return a + b;
}

const memoizedAdd = memoizeOne(add);

memoizedAdd(1, 2);
// add function: is called
// [new value returned: 3]

memoizedAdd(1, 2);
// add function: not called because same input as last time
// [cached result is returned: 3]

memoizedAdd(2, 3);
// add function: is called
// [new value returned: 5]

memoizedAdd(2, 3);
// add function: not called
// [cached result is returned: 5]

memoizedAdd(1, 2);
// add function is called again as only the last invocation is cached
// [result is returned: 3]

Task

Your task is to implement the memoizeOne function such that all the test cases pass.

How to run tests?

- npm install
- npx jest

Bonus Question 1

Click here for more details

this is treated as an input

Changes in the input invalidates the cache and calls the function again. this is also treated as an input. In other words, if this changes the function will be called again.

Example

function add(a, b) {
  return a + b;
}

const memoizedAdd = memoizeOne(add);

memoizedAdd.call({}, 1, 2);
// add function: is called with {}
// [new value returned: 3]

memoizedAdd.call({ a: 1 }, 1, 2);
// add function: is called with { a: 1 }
// [new value returned: 3]

Bonus Question 2

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Add a clear property to memoizeOne

Example:

memoizedAdd(1, 2);
// add function: is called
// [new value returned: 3]

memoizedAdd.clear();

memoizedAdd(1, 2);
// add function: is called because the cache was cleared
// [new value returned: 3]