Plz explain js code

Question

var arr=[9,8,7,6];
console.log(1 in arr) //true
console.log(9 in arr) //false
Why 1 in arr is true

Answer 1

7n4n03n , with "in" you are checking for element in the array if it's present in certain position. So there is an element on position 1, but there's no element on position 9 (the last position of the array is 3).