Question

Here’s the code that explains the question further:

function MyConstructor() {}
 var myobject = new MyConstructor();
 myobject.constructor == MyConstructor;     // true

function MyConstructor() {}
 MyConstructor.prototype = {};
 var myobject = new MyConstructor(); 
 myobject.constructor == MyConstructor;  // false

So, why is the second block false?

Answer 1

The constructor of the created object changes because the constructor of its prototype changes. This is why you generally shouldn’t overwrite the prototype. If you do, make sure to set it back later:

function MyConstructor() {}
MyConstructor.prototype = {};
MyConstructor.prototype.constructor = MyConstructor;
…
var myobject = new MyConstructor(); 
myobject.constructor == MyConstructor;  // false