I’m doing some quizes on Typescript and I stumble on this quiz. All of the correct answers are doing something like this:

if (this.score_ & ALLERGENS_SCORE[allergen]) {
  return true
}

Both of the this.score_ and ALLERGENS_SCORE[allergen] are number. I’m wondring what the single & do here.

I understand what it is for for types, but not on this scenario.

Here are some correct answer for this: this and this

I’d appreciate if someone can explain. Thanks in advance.