'includes()' is for string, not for array in Javascript?

Question

From: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object

Object.keys()
Returns an array containing the names of all of the given object's own enumerable string properties.

This says that 'includes' works on strings: https://www.w3schools.com/jsref/jsref_includes.asp

Then why is the following statement valid in the code shown in this SO thread?
https://stackoverflow.com/a/66758849/462608

const colorValues = Object.keys(this.colorValues);
const invalidColors = colors.filter(c => !colorValues.includes(c));

Answer 1

It exists on both prototypes: String.prototype.includes and Array.prototype.includes .

String.prototype.includes checks if the string contains the passed substring.

Array.prototype.includes checks if the array contains a particular value (with the SameValueZero algorithm).

Somewhat confusingly, they use the exact same name, but the logic employed is similar.