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Groups the elements into two arrays, depending on the provided function's truthiness for each element.
- Use
Array.prototype.reduce()to create an array of two arrays. - Use
Array.prototype.push()to add elements for whichfnreturnstrueto the first array and elements for whichfnreturnsfalseto the second one.
const partition = (arr, fn) =>
arr.reduce(
(acc, val, i, arr) => {
acc[fn(val, i, arr) ? 0 : 1].push(val);
return acc;
},
[[], []]
);const users = [
{ user: 'barney', age: 36, active: false },
{ user: 'fred', age: 40, active: true },
];
partition(users, o => o.active);
// [
// [{ user: 'fred', age: 40, active: true }],
// [{ user: 'barney', age: 36, active: false }]
// ]Recommended snippets
Partition array
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Applies
fnto each value inarr, splitting it each time the provided function returns a new value.Count grouped elements
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Groups the elements of an array based on the given function and returns the count of elements in each group.
Mapped array symmetric difference
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Returns the symmetric difference between two arrays, after applying the provided function to each array element of both.