how to show what vector has in javascript code example

Example 1: js array includes

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

Example 2: js array contains

let fruits = ["Banana", "Orange", "Apple", "Mango"];
let do_contain = fruits.includes("Mango"); // contain: true