Is There Something Like Mulitiset In Javascript?

I know that JavaScript now has sets, but I wonder if there is something to realize the function of multiSet, or if there is some framework that has the functions of multiset which

Solution 1:

There are no built-in multiset structure, but there are some libraries that have such:

• mnemonist → MultiSet
• TSTL → TreeMultiSet

Feel free to add your favorite library in this question.

Solution 2:

You can build your own multiset using the Builtin map type and numerical values:

classMultiset {
    _backing = newMap();
    add(value) {
        if (this._backing.has(value)) {
            this._backing.set(value, 1 + this._backing.get(value));
        } else {
            this._backing.set(value, 1);
        }
    }

    delete(value) {
        if (this._backing.get(value) > 0) {
            this._backing.set(value, this._backing.get(value) - 1);
        } else {
            //do nothing
        }
    }

    get(value) {
        if (this._backing.get(value) > 0) {
            returnthis._backing.get(value);
        } else {
            return0;
        }
    }
}