Understanding of the This keyword for nested functions in JavaScript

As we all know, in a method invocation, this refers to the object to which the method belongs, such as the following code:

Obj.test (Console.log (this// returns True

However, in nested functions, the situation has changed a lot. This needs to be divided into two situations: strict mode and non-strict mode

 //   obj = {test:  function   () { var  self = this  ; Console.log ( this  === obj);        True f ();  function   F () {Console.log ( 
     
      this 
      === obj); False Console.log (self  === obj);  True Console.log ( this  === window);        True}; }};obj.test ();  

//under strict mode"Use Strict"varobj ={test:function (){        varSelf = This; Console.log ( This===obj);        True f (); functionf () {Console.log ( This===obj); False Console.log ( self===obj); True Console.log ( This===window); False Console.log ( This===undefined);        True}; }};obj.test ();

Understanding of the This keyword for nested functions in JavaScript