jquery change background color user scroll

2019-01-06 12:40发布

站内问答 / jQuery
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Is it possible with jquery that when a user scrolls down the page that the background animate from 50% white to 90% white or someting?

So first it is the color rgba(255,255,255,.5) and when a user scroll 210px below the color become rgba(255,255,255,.9).

5条回答
Animai°情兽
2楼-- · 2019-01-06 13:06

here you go (this will change the page color to blue when you scroll more than 210px, and will revert back to red if you go back up):

$(document).ready(function(){       
            var scroll_pos = 0;
            $(document).scroll(function() { 
                scroll_pos = $(this).scrollTop();
                if(scroll_pos > 210) {
                    $("body").css('background-color', 'blue');
                } else {
                    $("body").css('background-color', 'red');
                }
            });
        });
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【Aperson】
3楼-- · 2019-01-06 13:11

with help of @redmoon7777

css

body{ height:5000px; }
.fifty { background:rgba(25,20,25,.5) }
.ninty {  background:rgba(25,20,25,.9) }

jQuery

 $(document).ready(function(){       
        var scroll_pos = 0;
        $(document).scroll(function() { 
            scroll_pos = $(this).scrollTop();
            if(scroll_pos > 210) {
                $("body").removeClass().addClass('ninty');
            } else {
                $("body").removeClass('ninty').addClass('fifty');
            }
        });
    });

DEMO

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小情绪 Triste *
4楼-- · 2019-01-06 13:22

Updated, more generic version:

var tStart = 100 // Start transition 100px from top
  , tEnd = 500   // End at 500px
  , cStart = [250, 195, 56]  // Gold
  , cEnd = [179, 217, 112]   // Lime
  , cDiff = [cEnd[0] - cStart[0], cEnd[1] - cStart[1], cEnd[2] - cStart[2]];

$(document).ready(function(){
    $(document).scroll(function() {
        var p = ($(this).scrollTop() - tStart) / (tEnd - tStart); // % of transition
        p = Math.min(1, Math.max(0, p)); // Clamp to [0, 1]
        var cBg = [Math.round(cStart[0] + cDiff[0] * p), Math.round(cStart[1] + cDiff[1] * p), Math.round(cStart[2] + cDiff[2] * p)];
        $("body").css('background-color', 'rgb(' + cBg.join(',') +')');
    });
});

In action

If you want a smooth, gradiated change when scrolling you should try

$(document).ready(function(){
    $(document).scroll(function() {
        var alpha = Math.min(0.5 + 0.4 * $(this).scrollTop() / 210, 0.9);
        var channel = Math.round(alpha * 255);
        $("body").css('background-color', 'rgb(' + channel + ',' + channel + ',' + channel + ')');
    });
});

JSFiddle

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We Are One
5楼-- · 2019-01-06 13:24

For smooth transition effect you should check scroll position, accordingly you can change bg-color. use .animate function of jquery.

I found the perfect what I was looking for here

http://jsfiddle.net/cgspicer/V4qh9/

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欢心
6楼-- · 2019-01-06 13:25

With animation

<html>
<head>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js"></script>
<!--for RGBA support. http://pioupioum.fr/sandbox/jquery-color/ -->
<script type="text/javascript" src="https://raw.github.com/piouPiouM/jquery-color/master/jquery.color.js"></script> 
<!--the magic -->
<script type="text/javascript">
$(document).ready(function(){
    $(document).scroll(function(){
        if($(this).scrollTop() > 210)
            $('#bk').animate({backgroundColor: 'rgba(255,255,255,.9)'}, 1000);
    });
});
</script>
</head>
<body style="background: black">
<div id="bk" style="background-color: rgba(255,255,255,.5); height: 200%; min-height: 400px">
<!--change this element's background transparency instead of body so that you will see the effect -->
</div>
</body>
</html>
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