Javascript object lost constructor when the prototype was changed

Question

In below code

var A = function() {};
var a = new A();
var b = new A();

A.prototype = {};

var c = new A();
console.log(a.constructor === b.constructor);
con         


        

Answer 1

When using function as an object constructor, its prototype.constructor is automatically created with function's property. So initially after setting up the A function you will have a constructor in A's prototype:

A.prototype.constructor

So when you assign A.prototype ={}, you lost that original constructor in A.prototype.

You may fix it with adding this after A.prototype ={} line

A.prototype.constructor = A;

Both console should log true