Looking for a quick way to see if an item is an array? Use the ES7 introduced Array.includes for a boolean return. The other way pre-ES7 is to convert the return into a boolean using a bitwise NOT operator which casts the result into a boolean. Finally, you can just use the more verbose conditional check for the array test. Read the docs for Array.includes here. Want to read even more? Check out the Array.prototype.includes proposal.