jQuery实现表格滚动定位指定行的方法

jQuery实现表格滚动定位指定行的方法

实现带有滚动条的表格并定位到特定行，操作并不复杂，仅需少量JavaScript代码即可完成。具体实现细节如下所示。

JavaScript代码部分

<strong><script type="text/javascript"> 
 function test(){ 
 var $objTr = $("#location"); //找到要定位的地方 tr 
 $objTr.css("background-color","lightgray"); //设置要定位地方的css 
 var objTr = $objTr[0]; //转化为dom对象 
 $("#dataDiv").animate({scrollTop:objTr.offsetTop},"slow"); //定位tr 
 } 
</script></strong> 

HTML结构部分

<body> 
 <h1>定位</h1> 
 <div id="dataDiv" style="overflow-x:hidden;overflow-y:auto;height:400px;width:450px;"> 
 <table id="tableId" style="width:400px;background-color:yellow" align="center" border="0"> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr <span style="color:#FF0000;">id="location"</span>><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 <tr><td>dddddddddddd</td><td>dddddddddd</td><td>ddddddddddddddddd<td/><td>dddddsererfd</td></tr> 
 </table> 
 </div> 
 <input type="button" value="定位到一行" onclick="test()"/> 
 </body> 

运行效果展示

尽管代码行数不多，但要深入理解其原理，需熟练掌握animate方法的用法，以及scrollTop和offsetTop属性的具体含义，这样才能在实际应用中灵活运用。

关键API原理解析

1. animate方法使用说明

animate() 方法用于执行针对CSS属性集的自定义动画。 该方法通过逐渐改变CSS样式，将元素从一种状态过渡到另一种状态，从而创建动画效果。 需要注意的是，只有数字类型的值才能创建动画（例如 "margin:30px"），字符串类型的值（如 "background-color:red"）无法直接生成动画效果。

2. scrollTop属性

scrollTop属性定义 在某些情况下，"元素内部内容"的高度可能会超过"元素容器本身"的高度。此时，scrollTop表示"元素内部内容"超出"元素上边界"的那部分高度值。

原理解释

假设内层元素高度为300px，外层元素高度为200px。由于内层高度大于外层，且外层设置了overflow为auto，因此外层元素右侧会出现垂直滚动条。 初始状态下，内层元素的上边界与外层元素的上边界重合，没有内容超出外层上边界，此时scrollTop的值为0。 当向下拖动滚动条时，超出外层上边界的内容逐渐增加，scrollTop的值即等于这些超出部分的高度。 当滚动条拖至最底部时，内层元素的下边界与外层元素的下边界重合。此时，超出外层上边界的内容高度 = 300px - 200px = 100px，即此时的scrollTop值为100。

3. offsetTop与offsetLeft等属性

假设 obj 代表某个HTML控件。 obj.offsetTop 表示 obj 距离上方或上层控件的位置，单位为像素，整型。 obj.offsetLeft 表示 obj 距离左方或上层控件的位置，单位为像素，整型。 obj.offsetWidth 表示 obj 控件自身的宽度，单位为像素，整型。 obj.offsetHeight 表示 obj 控件自身的高度，单位为像素，整型。

offsetParent属性

offsetParent属性返回一个对象引用，该对象是距离调用offsetParent的元素最近的、且在包含层次中最靠近的、并已进行CSS定位的容器元素。如果该容器元素未进行CSS定位，则offsetParent属性的取值为根元素（在标准兼容模式下为html元素；在怪异呈现模式下为body元素）的引用。当容器元素的style.display被设置为 "none" 时（IE和Opera除外），offsetParent属性返回null。 语法：parentObj = element.offsetParent 变量说明：parentObj 是一个元素的引用，当前元素的偏移量是相对于此元素计算的。

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