New attempts to inherit JavaScript class

What I've tried today is how to use inheritance mechanisms, multi-layer inheritance and more aspects of calling the parent class's constructs more like other languages.
What I hope to achieve:

Copy the codeThe code is as follows:

 
function A(){ 
alert('a'); 
} 
function B(){ 
this.$supClass(); 
alert('b'); 
} 
extend(B,A); 
function C(){ 
this.$supClass(); 
alert('c'); 
} 
extend(C,B); 
var c = new C(); 
alert( c instanceof A ); //true 
alert( c instanceof B ); //true 
alert( c instanceof C ); //true 

Example:

[Ctrl+A Select all Note:Introducing external Js requires refreshing the page before execution]

My extend is written like this:

Copy the codeThe code is as follows:

 
 function extend(subClass,supClass){ 
 var fun = function(){}, 
 prototype = ; 
  = ; 
  = new fun(); 
 for(var i in prototype){ 
 [i] = prototype[i]; 
 } 
 subClass.$supClass = supClass; 
 .$supClass = function(){ 
 var supClass = .$supClass; 
 if(typeof supClass == 'function'){ 
 (this,arguments); 
 this.$supClass = supClass; 
 } 
 }; 
  = subClass; 
 return subClass; 
 } 

Maybe you will ask, why not write this way:

Copy the codeThe code is as follows:

 
function extend(subClass,supClass){ 
var fun = function(){}, 
prototype = ; 
 = ; 
 = new fun(); 
for(var i in prototype){ 
[i] = prototype[i]; 
} 
.$supClass = function(){ 
(this,arguments); 
}; 
 = subClass; 
return subClass; 
} 

This seems to be fine, and only first-level inheritance will run well, but if multiple-level inheritance is incurred, it will cause a dead loop because:

Copy the codeThe code is as follows:

 
.$supClass = function(){ 
(this,arguments); 
}; 

This method will be overwritten and rewritten, causing a dead loop.
My approach is to use the $supClass attribute of the class to point to the parent class it inherits. There is also a $supClass method in the prototype. This $supClass must be executed in the class constructor for the first time. When executing prototype.$supClass, the $supClass of the class will be obtained through .$supClass, and then executed in this by applying. In this way, $subClass can obtain the class's parent class constructor and execute it according to different sources.