count

Count values which satisfy a test.

Alternatives: count, countAs.

function count(x, ft)
// x:  a set
// ft: test function (v, v, x)

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

var x = new Set([1, 2, 3, 4, 5]);
set.count(x, v => v % 2 === 1);
// → 3

set.count(x, v => v % 2 === 0);
// → 2

References

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