js centered floating advertisement

Program source code

var floatAd = {}; 
floatAd.getScrollTop = function(node) { 
var doc = node ? node.ownerDocument : document; 
return doc.documentElement.scrollTop || doc.body.scrollTop; 
}; 
floatAd.getScrollLeft = function(node) { 
var doc = node ? node.ownerDocument : document; 
return doc.documentElement.scrollLeft || doc.body.scrollLeft; 
}; 
floatAd.getBrowser = function() { 
var d = document.documentElement; 
return { 
width: window.innerWidth || (d && d.clientWidth) || document.body.clientWidth, 
height: window.innerHeight || (d && d.clientHeight) || document.body.clientHeight 
} 
}; 
floatAd.extend = function(destination, source) { 
for(var property in source) { 
destination[property] = source[property]; 
} 
return destination; 
}; 
/* 默认属性扩展 */ 
floatAd.setOptions = function(options) { 
this.options = { 
delay: 20, // 调整速率 
fadeTime: 1 // 自动消失时间 
}; 
return this.extend(this.options, options || {}); 
}; 
/* 类初始化 */ 
floatAd.init = function(id, options) { 
var _this = this; 
this.extend(this, this.setOptions(options)); 
this.control = document.getElementById(id); 
var _callback = function() { // fadeIn完成后的回调函数 
_this.timer = window.setInterval(function() { _this.scroll() }, _this.delay); // 滚动定位 
window.setTimeout(function() { _this.fadeOut() }, _this.fadeTime * 1000); // 在固定时间内消失 
} 
this.fadeIn(_callback); 
window.onresize = function() { _this.setCenter(); } 
}; 
/* 定时滚动 */ 
floatAd.scroll = function() { 
this.start = parseInt(this.control.style.top, 10); 
this.end = parseInt(this.getScrollTop() + this.getBrowser().height - this.control.clientHeight, 10); 
if(this.start != this.end) { 
this.amount = Math.ceil(Math.abs(this.end - this.start) / 15); /* 递减公式(this.start无限增大,整个分子无限减小,整个值就无限趋近于0) */ 
this.control.style.top = parseInt(this.control.style.top, 10) + ((this.end < this.start) ? -this.amount : this.amount) + &#39;px&#39;; 
} 
}; 
/* 目标居中并处于最底部 */ 
floatAd.setCenter = function() { 
this.top = this.getScrollTop() + floatAd.getBrowser().height; 
this.left = (this.getScrollLeft() + floatAd.getBrowser().width - this.control.clientWidth) / 2; 
this.control.style.top = this.top + &#39;px&#39;; 
this.control.style.left = this.left + &#39;px&#39;; 
}; 
/* fadeIn */ 
floatAd.fadeIn = function(callback) { 
var _this = this, _top = 0; 
this.control.style.display = &#39;block&#39;; // *要提前显示.不然无法取得clientWidth 
this.setCenter(); 
var _timer = window.setInterval(function() { 
_this.control.style.top = _this.getScrollTop() + _this.getBrowser().height - (++_top) + &#39;px&#39;; 
if(_top >= _this.control.clientHeight) { 
window.clearInterval(_timer); 
callback && callback(); 
} 
}, 2); 
}; 
/* fadeOut */ 
floatAd.fadeOut = function() { 
var _this = this, _num = 0, _top = _this.control.clientHeight; 
window.clearTimeout(this.timer); 
var _timer = window.setInterval(function() { 
if(_top <= 0) { 
window.clearInterval(_timer); 
_this.control.style.display = &#39;none&#39;; 
} else { 
_this.control.style.top = _this.getScrollTop() + _this.getBrowser().height - (--_top) + &#39;px&#39;; 
} 
}, 2); 
this.control.style.top = (parseInt(this.control.style.top, 10) + 100) + &#39;px&#39;; 
}; 
var newAd = &#39;start&#39;; 
document.getElementById(&#39;show&#39;).onclick = function() { 
if(newAd == &#39;start&#39;) { 
newAd = floatAd.init(&#39;ad&#39;, { fadeTime: 10 }); 
} 
}

Program principle
The entire advertising operation has four steps.
1. Hidden at the bottom of the page during initialization.
2. Raise from bottom to top. Until The entire advertisement floats out
3. Start detection. Keep the advertisement always at the bottom of the middle of the page when scrolling.
4. When the custom interval is reached, the advertisement automatically fades out.
The most important thing about the entire implementation is to control the advertisement The distance from the top of the document (non-window). (scrollTop + browser.clientHeight). Here is the code to get these values.
Get scrollTop, scrollLeft
Note that Chrome and Safari even in standard doc mode The root document is also document.body instead of document.documentElement

floatAd.getScrollTop = function(node) { 
var doc = node ? node.ownerDocument : document; 
return doc.documentElement.scrollTop || doc.body.scrollTop; 
}; 
floatAd.getScrollLeft = function(node) { 
var doc = node ? node.ownerDocument : document; 
return doc.documentElement.scrollLeft || doc.body.scrollLeft; 
};

Get the width and height of the visual window

floatAd.getBrowser = function() { 
var d = document.documentElement; 
return { 
width: window.innerWidth || (d && d.clientWidth) || document.body.clientWidth, 
height: window.innerHeight || (d && d.clientHeight) || document.body.clientHeight 
} 
};

Code idea flow
Initialization (init) -----> Set the center and hide the bottom (setCenter) -----> fadeIn) -----> The fade-in is completed. Call the callback function _callback ----->
Start the countdown to fade-out Time (setTimeout(fadeOut, time)), and bind the real-time detection function (scroll) -----> Reach the custom time to hide the advertisement (fadeOut)
Instructions for use
Instantiation function. Pass in the advertisement Container ID. Set the default attributes.
The default attributes are:

delay: 20, // 调整速率 
fadeTime: 1 // 自动消失时间(s) 
var newAd = 'start'; 
document.getElementById('show').onclick = function() { 
if(newAd == 'start') { 
newAd = floatAd.init('ad', { fadeTime: 10 }); 
} 
}

This is for the convenience of demonstration. So the advertisement is only initialized when the button is clicked. The advertisement can also be loaded during window.onload.

For more articles related to js centered floating ads, please pay attention to the PHP Chinese website!