This is a very good and simple example to control all of the other checkbox like gmail.
Label tag has been initialized with "masterCheckBoxCon" class and input element has been initialized with "masterCheckbox" id. Which will fire a "change" event. So to grab this element "masterCheckbox" id has been set.
Load only those image which is visible to visitor
After scrolling window beyond menu height, a floating bar appears at the top having same menu inside it.
A master checkbox which controls all checkbox.