javascript prototype -

i trying understand js prototype property: sample code

function container(param) {     this.member = param; }  var newc = new container('abc');   container.prototype.stamp = function (string) {     return this.member + string; }  document.write(newc.stamp('def'));  function box() {     this.color = "red";     this.member = "why"; }  container.prototype = new box(); box.prototype.test = "whatever"; var b = new box();  document.write(newc.test); 

here last line undefined - though container's prototype box , box's prototype has property test, why newc refers test in box doesnt work? can 1 please explain how 'prototype' works in above context.

thanks...

you setting container prototype box() after newc instance created.

reorder statements follows:

function container(param) {     this.member = param; }  function box() {     this.color = "red";     this.member = "why"; }  container.prototype = new box(); box.prototype.test = "whatever"; container.prototype.stamp = function (string) {     return this.member + string; }  //here containers prototype setup complete. var newc = new container('abc');  document.write(newc.stamp('def'));  document.write(newc.test);