node.js - why I can't "overwrite" a method in javascript? -


i override function of js object adding prototype.

var originalobject = function(){     this.somefun = function(){         // ...     } }  var otherobj = function(){     this.otherfun = function(){         originalobject.prototype.fun =  function(){             return 'this overwritten function.';         }         var o = new originalobject();         return o.fun()     } }

this way when execute new otherobj().otherfun() have expected result ('this overwritten function.'), if function i'm trying add part of originalobject

var originalobject = function(){     this.fun = function(){         return 'this original function';     }     this.somefun = function(){         // ...     } }

then result not expected one, infact new otherobj().otherfun() returns 'this original function'.

so, this way add method prototype , override it? , important why can't "overwrite" function in prototype?

in js objects there 2 levels depend on directly object , depend on directly prototype. , when call property in object, starts search root looks in branches. can see tree belowed picture: enter image description here


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