Counts occurrences of values. :package: :smiley_cat: :running: :vhs: :moon: :scroll: :newspaper: :blue_book:

Alternatives: count, countAs. Similar: count, partition.

This is part of package extra-array.

array.countAs(x, [fm]);
// x:  an array
// fm: map function (v, i, x)
// → Map {value => count}

const array = require("extra-array");

var x = [1, 1, 2, 2, 4];
array.countAs(x);
// Map(3) { 1 => 2, 2 => 2, 4 => 1 }

var x = [1, 2, 3, 4];
array.countAs(x, v => v % 2);
// Map(2) { 1 => 2, 0 => 2 }

References

• List-Extra.count: elm
• _.countBy: lodash
• count-iterable-values: @zeke