Are There Problems With Replacing A Javascript Constructor's .prototype Rather Than Adding To It?

I've come across another developer's code which does something like this to define a Javascript type: function Ninja() {} Ninja.prototype = { swingSword: function(){ return t

Solution 1:

When you "inherit" from another prototype you usually replace the entire prototype, if constructor is important you can re set it to the "correct" value:

varChild = function(){};
//"inherit" from ParentChild.prototype=Object.create(Parent.prototype);
//reset the constructorChild.prototype.constructor = Child;

So in your case just repair the constructor after you set the prototype:

varNinja = function() {}
Ninja.prototype = {
  swingSword: function(){
    returntrue;
  }
};
// you can put the next line anywhere you want to fix the problem// http://stackoverflow.com/a/16063711/1641941 under this.constructorNinja.prototype.constructor=Ninja;

Or:

varNinja = function() {}
Ninja.prototype = {
  swingSword: function(){
    returntrue;
  },
  constructor:Ninja
};