Function countBy

Counts the occurrences of each value in an array.

  • The values are converted to strings before being counted.
  • The result is an object whose keys are the values and whose values are the number of occurrences.

Example

const a = [1, 2, 3, 4, 5, 6, 7, 8, 9];
const isEven = (x: number) => x % 2 === 0;
const b = countBy(isEven)(a);
console.log(b); // { 'false': 5, 'true': 4 }