一些常用的JS功能函数(2009-06-04更新)

//获取对象 
function getObject(objectId,top) 
{ 
    doc = top?window.top.document:document; 
    if(typeof(objectId)!="object" && typeof(objectId)!="function") 
    { 
        if(doc.getElementById && doc.getElementById(objectId)) 
         { 
         // W3C DOM 
         return doc.getElementById(objectId); 
         } 
        else if(doc.getElementsByName(objectId)) 
        { 
            return doc.getElementsByName(objectId)[0]; 
        } 
         else if (doc.all && doc.all(objectId)) 
         { 
         // MSIE 4 DOM 
         return doc.all(objectId); 
         } 
         else if (doc.layers && doc.layers[objectId]) 
         { 
         // NN 4 DOM.. note: this won't find nested layers 
         return doc.layers[objectId]; 
         } 
         else 
         { 
         return false; 
         } 
    }else 
        return objectId; 
} 
//获取相对路径 
function getRelativePath() 
{ 
    var url = location.href;//当前url 
    var urlcs = String(location.search); 
    url = url.replace(urlcs,""); 
    var path = url.length - url.replace(/\//g,"").length - 3;    //层次为url包含/的长度-没有包含/的长度再减去项目头/的个数     var str = ""; 
    for(var i = 0; i < path; i++) 
    { 
     str += "../";//组合成一个相对路径的字符串返回 
    } 
    return str; 
} 
//加载其他JS文件或CSS文件 
function loadjscssfile(filename,filetype,chkonce) 
{ 
    filetype = !filetype?"js":filetype; 
    var had = false; 
    if(filetype=="js") 
    { 
        if(chkonce) 
        { 
            var allScripts = document.getElementsByTagName("script"); 
            for(var i=0;i<allScripts.length;i++) 
            { 
                try{ 
                    if(allScripts[i].src.indexOf(filename)>-1) 
                    { 
                        had = true; 
                        break; 
                    } 
                }catch(e){} 
            }     
        } 
        if(!had) 
        { 
            document.write("<script src=""+filename+"" src=""+filename+"" type='text/javascript'></script>"); 
        } 
    }else 
    { 
        if(chkonce) 
        { 
            var allCss = document.getElementsByTagName("link"); 
            if(allCss.length) 
            { 
                for(var i=0;i<allCss.length;i++) 
                { 
                    try{ 
                        if(allCss[i].href.indexOf(filename)>-1) 
                        { 
                            had = true; 
                            break; 
                        } 
                    }catch(e){} 
                } 
            } 
        } 
        if(!had) 
        { 
            document.write("<link type='text/css' rel='stylesheet' href=""+filename+"" href=""+filename+"" />"); 
        } 
    } 
} 
//定义根目录路径 
var ROOT_PATH = getRelativePath(); 
var JS_PATH = ROOT_PATH+'js/'; 
var AJAX_PATH = ROOT_PATH+'ajax/'; 
var CSS_PATH = ROOT_PATH+'css/'; 
var IMAGES_PATH = ROOT_PATH+'images/'; 
var EDITOR_PATH = ROOT_PATH+'uploadeditor/'; 
var PUB_PATH = ROOT_PATH+'uploadfile/'; 
//加载公共变量的JS 
loadjscssfile(JS_PATH+"globalPara.js"); 
//设置下拉表中某一项被选中 
function setSelOption(objId,vlu) 
{ 
    objId = getObject(objId); 
    for(var i=0;i<objId.options.length;i++) 
    { 
        if(objId.options[i].value==vlu) 
        { 
            objId.options[i].setAttribute("selected","selected"); 
            break; 
        } 
    } 
} 
//根据下拉表中的option文本设置某一项被选中 
function setTxtOption(objId,txt) 
{ 
    objId = getObject(objId);         
    for(var i=0;i<objId.options.length;i++) 
    { 
        if(objId.options[i].innerHTML==txt) 
        { 
            objId.options[i].setAttribute("selected","selected"); 
            break; 
        } 
    }     
} 
//设置单选按钮组中某一项被选中 
function setSelRadio(objName,vlu) 
{ 
    objName = document.getElementsByName(objName); 
    for(var i=0;i<objName.length;i++) 
    { 
        if(objName[i].value==vlu) 
        { 
            objName[i].setAttribute("checked","checked"); 
            break; 
        } 
    } 
} 
//根据ID设置复选框中某些项被选中 
//vlu 的格式为 ： 1,2,3 
function setSelCheckbox(prefix,vlu) 
{ 
    var _arr = vlu.split(","); 
    if(_arr!="") 
    { 
        for(var i=0; i<_arr.length; i++) 
        { 
            getObject(prefix+_arr[i]).checked = true; 
        } 
    } 
} 
//快捷输入，fromObj：来源对象，toObjId：目标对象的ID，txt为true时取toObjId的innerHTML值 
function fastInput(fromObj,toObjId,txt) 
{ 
    if(fromObj.value=='' || fromObj.value==0) return false; 
    txt = !txt ? false : txt; 
    var toObj = getObject(toObjId); 
    if(txt) 
    { 
        if(typeof (toObj.value) == 'undefined') 
             toObj.innerHTML = toTxt(fromObj.options[fromObj.selectedIndex].innerHTML); 
        else 
            toObj.value = toTxt(fromObj.options[fromObj.selectedIndex].innerHTML); 
    }else 
    { 
        if(typeof (toObj.value) == 'undefined') 
             toObj.innerHTML = fromObj.value; 
        else 
            toObj.value = fromObj.value;         
    } 
} 
/* 
IE6,IE7上传图片前预览图片 
IE6下还可以同时检测图片的大小 
size 单位为KB 
<style type="text/css"><!-- 
.newPreview 
{ 
    width:400px; height:300px; 
    FILTER: progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale) 
} 
.nodis{display:none;} 
--></style><style type="text/css" bogus="1"> 
.newPreview 
{ 
    width:400px; height:300px; 
    FILTER: progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale) 
} 
.nodis{display:none;}</style> 
<input type="file" name="litpic" onchange="PreviewImg(this,'newPreview','ndsPreview',400)" /> 
<div id="newPreview" class="newPreview"></div> 
<img id="ndsPreview" class="nodis" /> 
*/ 
function PreviewImg(imgFile,newPreview,ndsPreview,size) 
{ 
    newPreview = getObject(newPreview); 
    if(!imgFile || !imgFile.value || !newPreview){return}; 
    var patn = /\.jpg$|\.jpeg$|\.gif$|\.png$|\.bmp$/i; 
    if(patn.test(imgFile.value)) 
    { 
        try{newPreview.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgFile.value;}catch(e){} 
        if(navigator.appVersion.indexOf("MSIE 6.0",0)>-1) 
        { 
            size=!size?0:size; 
            ndsPreview = getObject(ndsPreview); 
            if(ndsPreview) 
            { 
                try{ndsPreview.attachEvent("onreadystatechange", function(){checkImgSize(ndsPreview,size)})}catch(e){} 
                ndsPreview.src = imgFile.value; 
            } 
        } 
    } 
    else 
    { 
        alert("您选择的不是图像文件,请重新选择."); 
    } 
} 
function PreviewImgNow(imgDiv,imgFile) 
{ 
    try{getObject(imgDiv).filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgFile}catch(e){}     
} 
//上传之前检测图片的大小 
//条件是在file改变时要触发函数将缩略图显示在img上 
//size 单位为KB 
function checkImgSize(img,size) 
{ 
    img = getObject(img); 
    if(img.readyState == "complete") 
    { 
        var limit = size * 1024; 
        if(img.fileSize > limit) 
        { 
            alert("出错！您上传的图片大小为"+(parseInt(img.fileSize/1024))+"KB,超过了"+size+"KB的限制，请重新上传"); 
            return false 
        }else 
            return true; 
    } 
    return true; 
} 
//检测客户端环境 
function ClientMentInfo() 
{ 
    var me = this;     
    var appVer = navigator.userAgent; 
    this.GetBrowserName = function (){ 
        if(appVer.indexOf("MSIE")>0) return "IE"; 
        else if(appVer.indexOf("Firefox")>0) return "Firefox"; 
        else if(appVer.indexOf("Chrome")>0) return "Chrome"; 
        else if(appVer.indexOf("Safari")>0) return "Safari"; 
        else if(appVer.indexOf("Camino")>0) return "Camino"; 
        else if(appVer.indexOf("Konqueror")>0) return "Konqueror"; 
        else return "其它"; 
    } 
    this.GetOSInfo = function (){ 
        var _pf = navigator.platform; 
        if(_pf == "Win32" || _pf == "Windows") 
        { 
            if(appVer.indexOf("Windows NT 6.0") > -1 || appVer.indexOf("Windows Vista") > -1) 
            { 
                return 'Windows Vista';     
            }else if(appVer.indexOf("Windows NT 6.1") > -1 || appVer.indexOf("Windows 7") > -1) 
            { 
                return 'Windows 7';     
            }else 
            { 
                try{ 
                    var _winName = Array('2000','XP','2003'); 
                    var _ntNum = appVer.match(/Windows NT 5.\d/i).toString(); 
                    return 'Windows ' + _winName[_ntNum.replace(/Windows NT 5.(\d)/i,"$1")]; 
                }catch(e){return 'Windows';} 
            } 
        }else if(_pf == "Mac68K" || _pf == "MacPPC" || _pf == "Macintosh") 
        { 
            return "Mac";             
        }else if(_pf == "X11") 
        { 
            return "Unix";     
        }else if(String(_pf).indexOf("Linux") > -1) 
        { 
            return "Linux";     
        }else 
        { 
            return "Unknow";     
        }         
    } 
    this.OS = me.GetOSInfo();        //操作系统类型 
    this.IeVer = null; 
    this.Bs_lang = (navigator.appName == 'Netscape'?navigator.language:navigator.browserLanguage);//浏览器语言版本 
    this.Bs_Name = me.GetBrowserName();        //浏览器名称 
    //浏览器版本 
    if(this.Bs_Name=='IE') 
    { 
        var _msie = appVer.match(/MSIE \d./i).toString(); 
        this.Bs_Version = this.IeVer = _msie.replace(/MSIE (\d)./i,"$1"); 
    }else 
    { 
        this.Bs_Version = appVer; 
    } 
    this.Ie6 = this.IeVer==6 ? true: false; 
    this.Ie7 = this.IeVer==7 ? true: false; 
    this.Ie8 = this.IeVer==8 ? true: false; 
} 
//客户端信息 
var CMInfo = new ClientMentInfo(); 
//IE6 下缓存背景图片 
if(CMInfo.Ie6) 
{ 
    document.execCommand("BackgroundImageCache", false, true); 
} 
//设置复选框全选或全不选 
function setAllCheckbox(formName,objName,num) 
{ 
    if(formName) 
        _arr = getObject(formName).elements[objName]; 
    else 
        _arr = typeof(objName)=="object"?objName:document.all(objName); 
    if(_arr) 
    { 
        if(num) 
        { 
            if (!_arr.length ) // 只有一个复选框，则length = undefined 
                _arr.checked = true; 
            else 
            { 
                for(var i=0; i<_arr.length; i++) 
                { 
                    _arr[i].checked = true; 
                } 
            } 
        }else 
        { 
            if (!_arr.length ) // 只有一个复选框，则length = undefined 
                _arr.checked = false; 
            else 
            { 
                for(var i=0; i<_arr.length; i++) 
                { 
                    _arr[i].checked = false; 
                } 
            } 
        } 
    } 
} 
//使当前页面跳到指定的页数页面 
function goPage(pageNum,pageStr) 
{ 
    window.location.href = "?np="+pageNum+pageStr; 
} 
//分别去字符串前后，左边，右边空格 
String.prototype.trim = function(){ return this.replace(/^\s+|\s+$/g,"")} 
String.prototype.ltrim = function(){ return this.replace(/^\s+/g,"")} 
String.prototype.rtrim = function(){ return this.replace(/\s+$/g,"")}

注意globalPara.js本作者常用到的一些每个站自己的常用变量和常量的文件，如果你不需要这样的文件，可把
//加载公共变量的JS
loadjscssfile(JS_PATH+"globalPara.js");

这两句删掉，不然会报错。

（2009-06-04更新）
将 ClientMentInfo类改成了兼容IE6,IE7,IE8,Vista,Windows 7和Firefox