README
Checks if map has a value. :running: :vhs: :package: :moon:
This is part of package extra-map.
map.isValueOn(x, v, [fn], [ths]);
// x: a map
// v: value?
// fn: map function (v, k, x)
// ths: this argument
const map = require('extra-map');
var x = new Map([['A', 1], ['B', 2], ['C', -3]]);
map.isValueOn(x, 3);
// false
map.isValueOn(x, 3, v => Math.abs(v));
// true