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Pursue Problem From Chap. 8. Ex. Membership.Js

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Last question of pursue section from chap. 8.


I'm trying to update membership.js script to understand event handling. I'have come up with following solution, it works fine, both for checking data and calculating cost. But, once that is done, the page is not enabled upon refresh. (Pressing refresh button on keyboard does not make the page active again.) What is the problem for that?


And, I would also like to know, is this the right answer? I mean, is it what is called as delegating event handling? Just want to make sure.........


I have used functions from utility file, to get reference to the form elements. ( those U.$() thing in the code).



function showData() {

'use strict';

var type = U.$('type');

var years = U.$('years');

var cost = U.$('cost');







function disableButton() {

'use strict';

U.$('submit').disabled = true;



function calculate(e) {

'use strict';

if (typeof e == 'undefined') e = window.event;

var cost;

var type = U.$('type');

var years = U.$('years');


if(years && years.value) {

years = parseInt(years.value, 10);


if(type && type.value && years && (years > 0))




switch (type.value) {

case 'basic' :

cost = 10.00;


case 'premium' :

cost = 15.00;


case 'gold' :

cost = 20.00;



} //End of switch.


cost *= years;

if(years > 1) {

cost *= 0.80;



U.$('cost').value = '$' + cost.toFixed(2);

U.$('submit').value = 'Submit your order';

U.addEvent(U.$('membership'), 'submit', showData);

U.addEvent(U.$('submit'), 'click', disableButton);

} else {

U.$('cost').value = 'Please enter valid values.';


if(e.preventDefault) {


} else {

e.returnValue = false;


return false;

} //End of calculate function.



window.onload = function() {

'use strict';


U.addEvent(U.$('membership'), 'submit', calculate);

U.addEvent(document, 'change', calculate);

U.$('submit').disabled = false;

U.$('submit').value = 'Calculate';



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