javascript - Why are some object methods declared differently than others -

so have this code 1 of examples class.

the method created point.new method.

point.prototype.tostring = function() {     return "(" + this.x + "," + this.y + ")"; };  point.new = function(x,y) {     var newobj = object.create(this.prototype);     this.call(newobj, x,y);     return newobj;   }; 

what don't understand why don't need declare method

point.prototype.new = function(){} 

(in fact wont compile when that)

point.prototype.tostring(){}  

method necessary. in both cases adding new method point object, how come 1 method being called on point , other being called on point.prototype (i believe points object?)

i'm not sure rule falls under, remember looking @ "adding property prototype rule" here.

but in case point not prototype since has no instances right?

the prototype used define methods can called on object created new point. e.g. can do:

var x = new point(15, 20); var str = x.tostring(); 

but wouldn't use x.new(), because .new() creating new objects, doesn't apply existing objects. defining point.new creates function can called as:

var y = point.new(10, 20);