countAs - nodef/extra-iterable GitHub Wiki

Count occurrences of values.

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

function countAs(x, fm)
// x:  an array
// fm: map function (v, i, x)

const xiterable = require('extra-iterable');

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

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

References