intersectionKeys - nodef/extra-map GitHub Wiki
Obtain keys present in all maps.
Similar: unionKeys, intersectionKeys.
function intersectionKeys(...xs)
// xs: maps
const map = require('extra-map');
var x = new Map(['a', 1], ['b', 2], ['c', 3], ['d', 4](/nodef/extra-map/wiki/'a',-1],-['b',-2],-['c',-3],-['d',-4));
var y = new Map(['b', 20], ['c', 30], ['e', 50](/nodef/extra-map/wiki/'b',-20],-['c',-30],-['e',-50));
map.intersectionKeys(x, y);
// → Set(2) { 'b', 'c' }