prototype problem

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function ABC(){ ... }

ABC.prototype.newMethod = function(){} //to create a new method

Then how about ABC.prototype = function() { ... } ?

Can I know what is the difference?

This is correct:

ABC.prototype.newMethod = function(){} //to create a new method

This is incorrect:

ABC.prototype = function() { ... }

What you may be looking for is:

ABC.prototype = {
  newMethod: function() {},
  anotherMethod: function() {}
};