i was traying to do the odin project exercises of javascript,
when I execute this line in the console
2 in [2,3,4,5]
it gives
true
but when I execute 3 in [3,4,5] in the console it gives back false I think it should also be true!!!
any explanation please thank you in advance
The in operator checks if a property key exists on an object. You can think of this array as having 4 keys.
const arr = [2, 3, 4, 5];
// arr has the keys `0`, `1`, `2`, and `3`.
console.log(arr[0], arr[1], arr[2], arr[3]);
So when you have the expression 2 in arr, you are checking if the array has a key 2, not if the value 2 exists in the array.
If you do want to check if an array contains an item, the includes() method would achieve what you want.
const arr = [2, 3, 4, 5];
arr.includes(2); // true
arr.includes(0); // false
It behaves like this because the in operator returns true if the specified property (not value) is in the specified object.
So in the first case the array has a length of 4 with indices 0,1,2,3 so the element with the index 2 exists.
In the second case there are 3 elements with indices 0,1,2, so there is no element with an index 3 that is why it returns false.
