Jquery/Javascript Opacity animation with scroll

Question

I'm looking to change the opacity on an object (and have the transition be animated) based on a users scroll. example(http://davegamache.com/)

I've searched everywhere like here, but it ends up pointing me to the waypoints plugin (http://stackoverflow.com/questions/6316757/opacity-based-on-scroll-position)

I've implemented the [waypoints][1] plugin and have the object fading once it's higher than 100px. [Using the offet attribute] but would like to basically control the opacity of an object and have the animation be visible like the above example.

I've searched all over- this is my last resort. Any help is greatly appreciated.

just add a starting and ending point to my answer will certainly be much more what you want — malko
– malko, Commented Jan 2, 2012 at 15:32

malko · Accepted Answer · 2012-01-02 15:32:15Z

27

working exemple with starting and ending point here: http://jsfiddle.net/z7E9u/1/

I copy paste basic code here

    var fadeStart=100 // 100px scroll or less will equiv to 1 opacity
    ,fadeUntil=200 // 200px scroll or more will equiv to 0 opacity
    ,fading = $('#fading')
;

$(window).bind('scroll', function(){
    var offset = $(document).scrollTop()
        ,opacity=0
    ;
    if( offset<=fadeStart ){
        opacity=1;
    }else if( offset<=fadeUntil ){
        opacity=1-offset/fadeUntil;
    }
    fading.css('opacity',opacity).html(opacity);
});

edited Jan 2, 2012 at 15:32

answered Jan 2, 2012 at 15:17

malko

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1 Comment

Ionut Necula Over a year ago

What would be the reverse to this? I mean to change opacity from 0 to 1.

maxedison · Accepted Answer · 2012-01-02 15:23:32Z

15

Here's a working example: http://jsfiddle.net/meEf4/

And the code:

var target = $('div');
var targetHeight = target.outerHeight();

$(document).scroll(function(e){
    var scrollPercent = (targetHeight - window.scrollY) / targetHeight;
    if(scrollPercent >= 0){
        target.css('opacity', scrollPercent);
    }
});

All we do is grab the current scroll position of the window, figure out what percentage of the element in question is now off-screen, and set its opacity with that percentage.

answered Jan 2, 2012 at 15:23

maxedison

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2 Comments

Soulremedy Over a year ago

This is great. I appreciate your quick response.

user3470625 Over a year ago

Brilliant solution! :)

Tom McDonough · Accepted Answer · 2017-03-18 10:59:52Z

2

As I have lower than 50 reputation I cannot reply to Lonut's question, how to do the reverse. Here is my code if you would like the reverse, quite handy for navigation bars.

$(window).scroll(function () {
        var offset = $(document).scrollTop()
        var opacity = 0;
        if (offset <= 0) {
            opacity = 0;
        } else if (offset > 0 & offset <= 200) {
            opacity = (offset - 1) / 200;
        }
        else {
            opacity = 1;
        }
        $('.black-background').css('opacity', opacity).html(opacity);
    });

answered Mar 18, 2017 at 10:59

Tom McDonough

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Comments

Rodik · Accepted Answer · 2012-01-02 15:18:34Z

0

I looked at the source code of that site. it uses: $(document).scrollTop(); to determine the scroll height, and $(window).scroll(function(){}) to bind an event listener to scrolling.

try this:

$(window).scroll(function(){
    var fromtop = $(document).scrollTop();       // pixels from top of screen
    $('#fademeout').css({opacity: 100-fromtop}); // use a better formula for better fading
});

answered Jan 2, 2012 at 15:18

Rodik

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Comments

André R. Kohl · Accepted Answer · 2020-03-30 13:25:12Z

0

I know I am a bit late to the party, but here's my approach:

$(window).scroll(function(){
  var st = $(window).scrollTop();
  var range = 300 // finetune this to the desired effect
  $('.yourelement').css("opacity", 1- st / range); // animate your element
});

answered Mar 30, 2020 at 13:25

André R. Kohl

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Comments

Munawir · Accepted Answer · 2016-09-23 04:33:42Z

-1

I like this solution

var fadeStart=100 // 100px scroll or less will equiv to 1 opacity
   ,fadeUntil=200 // 200px scroll or more will equiv to 0 opacity
   ,fading = $('#fading')
;

$(window).bind('scroll', function(){
    var offset = $(document).scrollTop()
        ,opacity=0
    ;
    if( offset<=fadeStart ){
        opacity=1;
    }else if( offset<=fadeUntil ){
        opacity=1-offset/fadeUntil;
    }
    fading.css('opacity',opacity).html(opacity);
});

How could you use the mouse scrolling for the fading ONLY until eg 0.2 opacity is reached and then scroll the page too? The solutions i found so far disable the mouse scrolling function completely

edited Sep 23, 2016 at 4:33

Munawir

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answered Mar 24, 2015 at 17:15

Martin

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