JavaScript function object and prototype

In JavaScript, function is also an object. Example:
function myfun(price){
    this.price = price;
}

We can access the  function  methods and properties when we create new myfunc function object.
var myfunc1 =new myfunc(200);
myfunc1.price will be equal to 200.

One of the property of the JavaScript function object is prototype. Prototype is also an object.
Example 1: use the prototype  to add a property to the function object
myfunc.prototype.tax=null;
myfunc1.tax=24;
myfunc has a  new property tax and new object myfunc1.tax equal to 24.

Example 2: use the prototype  to add a method to the function object
 myfunc.prototype.totalprice = function(){
       return this.price+this.tax;
}

myfunc1.totalprice will be equal to 124.