Javascript公共脚本库系列(一):弹出层脚本_javascript技巧

/* ==================== ScriptHelper 开始 ==================== */
/* scriptHelper 脚本帮助对象.
创建人: ziqiu.zhang 2008.3.5
添加函数:
getScroll():得到鼠标滚过的距离-兼容XHTML
getClient():得到浏览器当前显示区域的大小-兼容XHTML
showDivCommon():显示图层.
使用举例:


*/
function scriptHelper()
{
}

// 得到鼠标滚过的距离 scrollTop 与 scrollLeft
/* 用法与测试:
var myScroll = getScroll();
alert("myScroll.scrollTop:" + myScroll.scrollTop);
alert("myScroll.scrollLeft:" + myScroll.scrollLeft);
*/
scriptHelper.prototype.getScroll = function ()
{
var scrollTop = 0, scrollLeft = 0;
scrollTop = (document.body.scrollTop > document.documentElement.scrollTop)? document.body.scrollTop:document.documentElement.scrollTop;
if( isNaN(scrollTop) || scrollTop <0 ){ scrollTop = 0 ;}
scrollLeft = (document.body.scrollLeft > document.documentElement.scrollLeft )? document.body.scrollLeft:document.documentElement.scrollLeft;
if( isNaN(scrollLeft) || scrollLeft <0 ){ scrollLeft = 0 ;}
return { scrollTop:scrollTop, scrollLeft: scrollLeft};
}
// 得到浏览器当前显示区域的大小 clientHeight 与 clientWidth
/* 用法与测试:
var myScroll = getScroll();
alert("myScroll.sTop:" + myScroll.sTop);
alert("myScroll.sLeft:" + myScroll.sLeft);
*/
scriptHelper.prototype.getClient = function ()
{
//判断页面是否符合XHTML标准
var isXhtml = true;
if( document.documentElement == null || document.documentElement.clientHeight <= 0)
{
if( document.body.clientHeight>0 )
{
isXhtml = false;
}
}
this.clientHeight = isXhtml?document.documentElement.clientHeight:document.body.clientHeight;
this.clientWidth = isXhtml?document.documentElement.clientWidth:document.body.clientWidth;
return {clientHeight:this.clientHeight,clientWidth:this.clientWidth};
}

// 显示图层,再次调用则隐藏
/* 参数说明:
sObj : 要弹出图层的事件源
divId : 要显示的图层ID
sObjHeight : 事件源的高度,默认为20.需要手工传入是因为对于由于事件源对象可能是各种HTML元素,有些元素高度的计算无法跨浏览器通用.
moveLeft : 手工向左移动的距离.不移动则为0(默认).
divObjHeight: 弹出层的高度.如果传入大于0的此参数, 则当事件源下方空间不足时,在事件源上方弹出层.如果不传此参数则一直在事件源下方弹出.
用法与测试:

*/
scriptHelper.prototype.showDivCommon = function (sObj,divId, sObjHeight, moveLeft, divObjHeight)
{
//取消冒泡事件
if( typeof(window)!='undefined' && window != null && window.event != null )
{
window.event.cancelBubble = true;
}
else if( ScriptHelper.showDivCommon.caller.arguments[0] != null )
{
ScriptHelper.showDivCommon.caller.arguments[0].cancelBubble = true;
}
//参数检测.如果没有传入参数则设置默认值
if( moveLeft == null )
{
moveLeft = 0;
}
if( sObjHeight == null )
{
sObjHeight = 20;
}
if(divObjHeight == null)
{
divObjHeight = 0;
}

var divObj = document.getElementById(divId); //获得图层对象
var sObjOffsetTop = 0; //事件源的垂直距离
var sObjOffsetLeft = 0; //事件源的水平距离
var myClient = this.getClient();
var myScroll = this.getScroll();
var sWidth = sObj.width; //事件源对象的宽度
var sHeight = sObjHeight; //事件源对象的高度
var bottomSpace; //距离底部的距离
/* 获取事件源控件的高度和宽度.*/
if( sWidth == null )
{
sWidth = 100;//无法获取则为100
}
else
{
sWidth = sWidth + 1; //留出1px的距离
}

if( divObj.style.display.toLowerCase() != "none" )
{
//隐藏图层
divObj.style.display = "none";
}
else
{
if( sObj == null )
{
alert("事件源对象为null");
return false;
}
/* 获取事件源对象的偏移量 */
var tempObj = sObj; //用于计算事件源坐标的临时对象
while( tempObj && tempObj.tagName.toUpperCase() != "BODY" )
{
sObjOffsetTop += tempObj.offsetTop;
sObjOffsetLeft += tempObj.offsetLeft;
tempObj = tempObj.offsetParent;
}
tempObj = null;

/* 获取距离底部的距离 */
bottomSpace = parseInt(myClient.clientHeight) - ( parseInt(sObjOffsetTop) - parseInt(myScroll.scrollTop)) - parseInt(sHeight);
/* 设置图层显示位置 */
//如果事件源下方空间不足且上方控件足够容纳弹出层,则在上方显示.否则在下方显示
if( divObjHeight>0 && bottomSpace < divObjHeight && sObjOffsetTop >divObjHeight )
{
divObj.style.top = ( parseInt( sObjOffsetTop ) - parseInt( divObjHeight ) - 10).toString() + "px";
}
else
{
divObj.style.top = ( parseInt( sObjOffsetTop ) + parseInt( sHeight ) ).toString() + "px";
}
divObj.style.left = ( parseInt( sObjOffsetLeft ) - parseInt( moveLeft ) ).toString() + "px";
divObj.style.display="block";
}
}

// 关闭图层
/* 参数说明:
divId : 要隐藏的图层ID
用法与测试:
ScriptHelper.closeDivCommon('testDiv');
*/
scriptHelper.prototype.closeDivCommon = function (divId)
{
//
var divObj = document.getElementById(divId); //获得图层对象
if( divObj != null )
{
divObj.style.display = "none";
}
}
//建立scriptHelper类的一个实例对象.全局使用.
var ScriptHelper = new scriptHelper();
/* ==================== ScriptHelper 结束 ==================== */