The difference between JavaScript instanceof and typeof

Referenced from: http://www.cnblogs.com/eoiioe/archive/2008/12/31/1366081.html

Both instanceof and typeof can be used to determine whether a variable is empty or what type of variable it is.

typeof is used to get the type of a variable, typeof generally can only return the following results:Number,boolean,string,function,object, Undefined.

We can use TypeOf to get the existence of a variable, such as if (typeof a!= "undefined") {}, instead of using if (a) because if a does not exist (not declared) then an error occurs, for array, Special objects such as null use TypeOf to return object, which is the limitation of typeof.

choose to use instanceof if we want to get an object that is an array, or whether a variable is an instance of an object.

instanceof is used to determine whether a variable is an instance of an object, such as Var a=new array (), alert (a instanceof array), returns True, and alert (a Instanceof object) also returns true because the array is a subclass of Object.

Again such as: function Test () {};var a=new test (); alert (a instanceof test) returns True.

When it comes to instanceof we need to insert one more question, that is, the function of arguments, we all may think arguments is an array, But if you use instaceof to test you will find that arguments is not an array object, though it looks like.

Other than that:

Test var a=new Array (), if (a instanceof Object) alert (' Y '), Else alert (' N ');
Get ' Y '

But if (window instanceof Object) alert (' Y '), Else alert (' N ');

Get ' N '

So, the object in the instanceof test here refers to the object in the js syntax, not the Dom model objects.

There are some differences between using typeof
Alert (typeof (window) will have an object

The difference between JavaScript instanceof and typeof