JS determine object type method _javascript skill

1, typeof
Supports basic types of acquisition, such as Boolean, string, number, function, object, undefined
Usage:
var v = true;//"string",
typeof V; Boolean
Ps:array/date/null are object,undefined for undefined.
2, instanceof
When you determine whether a value is a function or object, you can use instanceof to learn more about it
Usage:
var v = new Date ();
V instanceof object;//true
V instanceof date;//True
3, constructor
A more one-step method than instanceof, a constructor property.
var v = new Date ();
V.constructor = = Object;//true Note that the right side of the equals sign is the constructor of the type to be detected
V.constructor = = Date;//true