How to determine whether an object is an array? Is a more common problem. I summarize the four methods of the chain, as follows.
The First method
Array.prototype.isPrototypeOf(obj) // Determine if the Array is on the prototype object of obj. Return true/false
The Second method
obj instanceof Array //return true/false
The Third method
Object.prototype.toString.call(obj) //return [Object Array]
The Fourth method
Array.isArray (obj) // There are compatibility issues
personally recommend the third method. The return is clearer. It is possible to clearly determine what type of current object is not only to determine the array.