In the old times the only way to store some data list was by using array:
const users = ['Moshe','Vasia'];
These days some new players entering the scene:The Set
It has "add", "delete", "clear" (for remove all the entries) methods
const users = new Set(['Moshe', 'Vasia']);
users.add('Ivan'); // will add one more entry
It also has "has" method for checking if item exists in Set:
console.log(users.has('Ivan')); // will print true
As far as I can see - the most cool feature (and may be a purpose of Set`s creation) - is uniqness:
Set will not allow duplicates:
console.log(new Set([1,2,4,3,1])); // will 1,2,4,3
BUT (there must be always a "but")all those cool features will not help you with following structure: (if the array consist of objects)
const users = new Set([
{id:'123', name: 'Moshe'},
{id:'124', name: 'Vasia'},
])
You will not be able to check if somebody with id '123' exist in Set using "has" method:
console.log(users.has('123')); // will be false
Also: it appears that Set not has a support for accessing entries by index
And if you want to access first entry you will need to use something like this:
const user = users.values().next().value;
console.log(user); // will print "{id:123, name: 'Moshe'}"
Disappointing!So, when this "Set" might be needed? you may ask...
The answer I found so far - is following scenario:
Remove duplicates:
const users = [
{id:123, name: 'Moshe'},
{id:124, name:'Vasia'},
{id:125, name:'Ivan'},
{id:123, name: 'Moshe'}// same Moshe one more time
];
const dedupedIds = Array.from(new Set(users.map(({id}) => id)))
console.log(dedupedIds); // will print 123,124,125
Conclusion
Although Set looks cool and promising - it seems there is not a much cases to use it (As far as I can see now)
