What is an Array?
Example Code of fromIndex with Array:
// var arr = ['red', 'blue', 'yellow'];
--> When the default index sets at 0
arr.includes('yellow', 3); // false
arr.includes('yellow', 100) // false
--> if the computed index is less than 0
// array length is 3
// fromIndex is -100
// computed index is 3 + (-100) = 97
var arr = ['red', 'blue', 'yellow'];
arr.includes( 'red', -100); //true
arr.includes( 'blue', -100); //true
arr.includes( 'yellow', -100); //true