6 lines
185 B
JavaScript
6 lines
185 B
JavaScript
const countBy = (arr, fn) =>
|
|
arr.map(typeof fn === 'function' ? fn : val => val[fn]).reduce((acc, val, i) => {
|
|
acc[val] = (acc[val] || 0) + 1;
|
|
return acc;
|
|
}, {
|
|
module.exports = countBy; |