MutableArray#includes()

Returns true if the passed object can be found in the array. This method is a Polyfill for ES 2016 Array.includes. If no startAt argument is given, the starting location to search is 0. If it's negative, searches from the index of this.length + startAt by asc.

[1, 2, 3].includes(2);     // true
[1, 2, 3].includes(4);     // false
[1, 2, 3].includes(3, 2);  // true
[1, 2, 3].includes(3, 3);  // false
[1, 2, 3].includes(3, -1); // true
[1, 2, 3].includes(1, -1); // false
[1, 2, 3].includes(1, -4); // true
[1, 2, NaN].includes(NaN); // true