How to check if item is in array in JavaScript?

To check if item is in array in JavaScript, we use the indexOf method.

For instance, we write

const blockedTile = ["118", "67", "190", "43", "135", "520"];

if (blockedTile.indexOf("118") !== -1) {
  // ...
}

to call blockedFile.indexOf with the item we’re looking for to see it’s in the blockedFile array.

It returns the index of the item if it exists and -1 otherwise.

If it returns something bigger than -1, then the item is found.