JavaScript 配列の積集合と和集合

配列の積集合

a1 = [1,1,2,3,3,4]
ary = []; a1.forEach(function(e){if(!ary.includes(e)){ary.push(e)}});
a2 = [1, 2, 5, 6, 4]
ary.filter(e => a2.includes(e))

配列の和集合

a1 = [1,1,2,3,3,4, 7]
a2 = [1, 2, 5, 6, 4, 8]

var a = a1.slice()
for(var i = 0; i < a2.length; i++){
    a.push(a2[i])
}
ary = []; a.forEach(function(e){if(!ary.includes(e)){ary.push(e)}});