countAs

Count occurrences of values.

Alternatives: count, countAs.

function countAs(x, fm)
// x:  entries
// fm: map function (v, k, x)

const entries = require('extra-entries');

var x = [["a", 1], ["b", 1], ["c", 2], ["d", 2], ["e", 4]];
entries.countAs(x);
// → Map(3) { 1 => 2, 2 => 2, 4 => 1 }

var x = [["a", 1], ["b", 2], ["c", 3], ["d", 4]];
entries.countAs(x, v => v % 2);
// → Map(2) { 1 => 2, 0 => 2 }

References

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