angular typescript filter array group by attribute

1function groupBy(list, keyGetter) {
2    const map = new Map();
3    list.forEach((item) => {
4         const key = keyGetter(item);
5         const collection = map.get(key);
6         if (!collection) {
7             map.set(key, [item]);
8         } else {
9             collection.push(item);
10         }
11    });
12    return map;
13}
14
15// example usage
16
17const pets = [
18    {type:"Dog", name:"Spot"},
19    {type:"Cat", name:"Tiger"},
20    {type:"Dog", name:"Rover"}, 
21    {type:"Cat", name:"Leo"}
22];
23    
24const grouped = groupBy(pets, pet => pet.type);
25    
26console.log(grouped.get("Dog")); // -> [{type:"Dog", name:"Spot"}, {type:"Dog", name:"Rover"}]
27console.log(grouped.get("Cat")); // -> [{type:"Cat", name:"Tiger"}, {type:"Cat", name:"Leo"}]
28    
29