解析javascript 实用函数的使用详解

代码如下:
function addBookMark(url, title){
//将网页添加到收藏addBookMark(window.location,document.title)
    if(document.all){
      window.external.addFavorite(url,title);
    }else if (window.sidebar){
      window.sidebar.addPanel(title,url,'');
    }else{
      alert('添加失败');
    }
}  

function setHomepage(obj,url) {
// setHome(this, window.location)
    try {  
        obj.style.behavior = 'url(#default#homepage)';  
        obj.setHomePage(url);  
    } catch (e) {  
        if (window.netscape) {  
            try {  
                netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");  
            } catch (e) {  
                alert('此操作被浏览器拒绝！/n请在浏览器地址栏输入"about:config"并回车/n然后将 [signed.applets.codebase_principal_support]的值设置为"true",双击即可。');  
            }  
            var prefs = Components.classes['@mozilla.org/preferences-service;1'].getService(Components.interfaces.nsIPrefBranch);  
            prefs.setCharPref('browser.startup.homepage', vrl);  
        }  
    }  
}  

function boxMove(box){
//可移动的层
    var w = box.scrollWidth,h = box.scrollHeight;
    var iWidth = document.documentElement.clientWidth;
    var iHeight = document.documentElement.clientHeight;    
    var moveX = 0,moveY = 0,moveTop = 0,moveLeft = 0,moveable = false;
    box.onmousedown = function(e){   
    moveable = true;    
    e = window.event?window.event:e;
    moveX = e.clientX-box.offsetLeft;       
    moveY = e.clientY-box.offsetTop;
    box.style.zIndex++;
    }
    document.onmousemove = function(e){
        if(moveable){
            e = window.event?window.event:e;