Scroll Down the page event

How can I catch the event of scroll down the page? I mean I want to have function call if the user scroll down to the end of the page?

Using Prototype JS or pure Javascr开发者_开发问答ipt.

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You would need to bind a scroll event to the window and then check the scroll position.

$(window).observe('scroll', function(event) {
    var scrollOffsets = document.viewport.getScrollOffsets();
    var scrollTop = scrollOffsets.top;
});

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Using prototypejs try this,

$(document).observe('scroll', function(event) {     
  alert("the page has been scrolled"); 
  //call the user function
});

or try this,

Event.observe(window,'scroll', function(event) {        alert("the page has been scrolled");    
//call the user function 
});