Check whether an array includes a certain value

The includes() method determines whether an array includes a certain value among its entries, returning true or false as appropriate.

Option: fromIndex is the position in this array at which to begin searching for valueToFind

const languages = [
  "JavaScript", "TypeScript", "Ruby", "Python"
]

languages.includes("Ruby")      // true
languages.includes("Ruby", 2)   // true
languages.includes("Ruby", 3)   // false
languages.includes("Ruby", -1)  // false