Aggregation methods are functions that operate on an array of values and return a single value that represents some kind of summary or aggregation of the original data.
The countBy function takes an array of objects and returns an object where each key represents a value of the input array and the corresponding value represents the count of that value in the array. This function only works with non-primitive types.
keys(required): The keys of the object to use for grouping the values in the array.
- An object where each key represents a value of the input array and the corresponding value represents the count of that value in the array.
const arr = [
{ name: "John", age: 30 },
{ name: "Jane", age: 25 },
{ name: "John", age: 25 },
{ name: "Jane", age: 30 },
{ name: "John", age: 30 },
];
const result = arr.countBy("name", "age");
console.log(result);
// Output:
// {
// "John.30": 2,
// "Jane.25": 1,
// "John.25": 1,
// "Jane.30": 1
// }- This function is made for arrays which contains non-primitive elements like objects.
Returns an object with the count of each primitive value in the input array or the count of specified primitive values.
...keys(Optional):- primitive values to count in the input array.
Record<string, number> - An object with primitive values as keys and their counts as values.
const arr = [1, 2, 3, 1, 2, 'test', 'test'];
const result = arr.countValues();
// result: { '1': 2, '2': 2, '3': 1, 'test': 2 }
const result2 = arr.countValues(1, 2);
// result2: { '1': 2, '2': 2 }- This function is made for arrays which contains primitive values.
Returns an array containing all elements from the first array that are not present in any of the other arrays.
comma seperated arrays(required):- Arrays to find the difference with.
- The difference between the first array and the other arrays.
const arr1 = [1, 2, 3, 4, 5];
const arr2 = [3, 4, 5, 6, 7];
const arr3 = [5, 6, 7, 8, 9];
const result = arr1.difference(arr2, arr3); // [1, 2]Groups array of objects by the given key.
- key (required):- key of the object to group by
- Object with grouped key's values as properties and grouped values as arrays
const data = [
{ name: "Alice", city: "New York", age: 25 },
{ name: "Bob", city: "New York", age: 30 },
{ name: "Charlie", city: "San Francisco", age: 25 },
{ name: "Dave", city: "San Francisco", age: 30 },
];
const example1 = data.groupBy('city');
// Output:
// {
// "New York": [
// { name: "Alice", city: "New York", age: 25 },
// { name: "Bob", city: "New York", age: 30 }
// ],
// "San Francisco": [
// { name: "Charlie", city: "San Francisco", age: 25 },
// { name: "Dave", city: "San Francisco", age: 30 }
// ]
// }
- This function is supposed to work only with array of objects. Else expect for unexpected behaviour.
- Currently only one key is supported. It will be updated to take multiple arguments and to group by multiple values.
Returns the intersection of two arrays, i.e., an array of elements that are present in both arrays.
- array (required):- The array to intersect with
- An array containing the intersection of the two arrays.
const arr1 = [1, 2, 3, 4, 5];
const arr2 = [3, 4, 5, 6, 7];
const intersectArr = arr1.intersect(arr2); // [3, 4, 5]
- This function is also compatible with arrays which contain non-primitive values.
Returns the union of two arrays, i.e., an array of all elements from both arrays with duplicates removed.
- array (required):- The array to union with
- An array containing the union of the two arrays.
const arr1 = [{ id: 1, name: "Alice" }, { id: 2, name: "Bob" }, { id: 3, name: "Charlie" }];
const arr2 = [{ id: 2, name: "Bob" }, { id: 3, name: "Charlie" }, { id: 4, name: "David" }];
// Call the function
const result = arr1.union(arr2);
// Output the result
console.log(result);
// [{ id: 1, name: "Alice" },{ id: 2, name: "Bob" },{ id: 3, name: "Charlie" },{ id: 4, name: "David" }]- This function is also compatible with arrays which contain non-primitive values.