js method to determine object type_javascript skills

1. typeof
supports the acquisition of basic types, such as: boolean, string, number, function, object, undefined
Usage:
var v = true;//"string",
typeof v; //boolean
PS: Array/Date/null, etc. are all objects, undefined is undefined
2, instanceof
When determining whether a value is a function or object , you can use instanceof to learn more details
Usage:
var v = new Date();
v instanceof object;//true
v instanceof Date;// true
3. constructor
A more one-step method than instanceof, constructor attribute.
var v = new Date();
v.constructor == Object;//true Note that the right side of the equal sign is the constructor of the type to be detected
v.constructor == Date;//true