Typescript Generics in classes

typescript-generics.ts

class Queue<T> {
    private data: T[] = [];

    push(item: T) {
        this.data.push(item);
    }

    pop(): T | undefined {
        return this.data.shift();
    }
}


let obj = new Queue<number>();
obj.push(1);
obj.push("2"); Error: Argument of type '"2"' is not assignable to parameter of type 'number'
obj.push(3);

console.log(obj.pop());
console.log(obj.pop());
console.log(obj.pop());