javascript每日一练（五）——BOM

一、BOM打开，关闭窗口

　　window.open();　　window.close();

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<script>
window.onload = function()
{
    var oBtn = document.getElementById('btn1');
    var oBtn2 = document.getElementById('btn2');

    oBtn.onclick = function(){
        var oNewWin = window.open('about:blank');

        oNewWin.document.write(123);
    };

    oBtn2.onclick = function(){
        window.close();
    };            

};
</script>
</head>

<body style="height:2000px;">
<button id="btn1">open</button><button id="btn2">close</button>
</body>
</html>

二、BOM常用属性

　　window.navigator.userAgent;　　window.loaction;

三、BOM侧边栏随窗口滚动(广告浮窗)

　　可视区高/宽度:　　document.documentElement.clientHeight/clientWidth;

　　滚动条滚动距离：　document.documentElement.scrollTop || document.body.scrollTop;

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
#div1{ width:100px; height:100px; background:red; position:absolute; right:0; top:0;}
</style>
<script>
window.onload = window.onresize = window.onscroll = function(){
    var oDiv = document.getElementById('div1');
    var iScrollTop = document.body.scrollTop || document.documentElement.scrollTop;    //获取滚动条距离顶部高度
    var iH = document.documentElement.clientHeight;    //获取可视区高度

    oDiv.style.top = iScrollTop + (iH - oDiv.offsetHeight) / 2 + 'px';
};
</script>
</head>

<body style="height:2000px;">
<div id="div1"></div>
</body>
</html>

四、BOM回到顶部　　

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
button{ position:fixed; right:0; bottom:0;}
</style>
<script>
window.onload = function(){
    var oBtn = document.getElementById('btn1');
    var timer = null;
    var bSys = true;

    window.onscroll = function(){
        if(!bSys){
            clearInterval(timer);
        }        

        bSys = false;
    };

    oBtn.onclick = function(){
        timer = setInterval(function(){
            var scrollTop = document.body.scrollTop || document.documentElement.scrollTop;
            var iSpeed = Math.floor((-scrollTop / 8));

            if(scrollTop == 0){
                clearInterval(timer);
            }

            bSys = true;
            document.documentElement.scrollTop = document.body.scrollTop = scrollTop + iSpeed;
        }, 30);
    };
};
</script>
</head>

<body style="height:2000px;">
<button id="btn1">回到顶部</button>
</body>
</html>