Include() of array

Array of includes( ) Usage of , Used to determine whether the specified value is included in the array , If so, return to true, conversely false.

grammar ：includes（searchElement,fromIndex）

searchElement     must . The value of the element to look for .
fromIndex     Optional . Start at this index to find searchElement. If it's negative , Then in ascending order from array.length + fromIndex Start searching the index of . The default is 0.

let arr = [1, 2, 3, 4]
console.log(arr.includes(1)); //true
console.log(arr.includes(5)); //false