js实现滚动条滚动到某个位置便自动定位某个tr_javascript技巧
程序员文章站
2022-04-09 20:45:41
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要实现带滚动条的table，定位到某个tr，其实是很简单的，只有几行js代码就可以完成，具体内容如下
js代码
<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
<body>
<h1>定位</h1>
<p 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>
</p>
<input type="button" value="定位到一行" onclick="test()"/>
</body>
虽说是几行代码，但要彻底弄懂。要熟悉animate的使用，scrollTop，.offsetTop的意思方可得心应手。
1. animate的使用说明：
animate() 方法执行 CSS 属性集的自定义动画。
该方法通过CSS样式将元素从一个状态改变为另一个状态。CSS属性值是逐渐改变的，这样就可以创建动画效果。 只有数字值可创建动画（比如 "margin:30px"）。字符串值无法创建动画（比如 "background-color:red"）。
2. scrollTop
scrollTop属性
有些情况下,“元素中内容”的高度会超过“元素本身”的高度, scrollTop指的是“元素中的内容”超出“元素上边界”的那部分的高度。
解释： 内层元素的高度值300px > 外层元素的高度值200px,因此“外层元素的内容”(也就是“内层元素”)无法完全显示，而外层元素把overflow设置为auto，因此外层元素的右侧会出现竖直滑动条 初始状态下，“内层元素的上边界”和“外层元素的上边界”重合，没有任何内容超过“外层元素的上边界”，此时scrollTop属性的值为0。
当向下拖动滚动块时，超过“外层元素的上边界”的内容会逐渐增多，scrollTop值就等于这些超出部分的高度。 当拖动滚动块到最底部时，“内层元素的下边界”和“外层元素的下边界”重合，此时,超过“外层元素的上边界”的内容的高度=300px-200px=100px，也就是此时的scrollTop值。
3..offsetTop，offsetLeft等
假设 obj 为某个 HTML 控件。
obj.offsetTop 指 obj 距离上方或上层控件的位置，整型，单位像素。
obj.offsetLeft 指 obj 距离左方或上层控件的位置，整型，单位像素。
obj.offsetWidth 指 obj 控件自身的宽度，整型，单位像素。
obj.offsetHeight 指 obj 控件自身的高度，整型，单位像素。
offsetParent
offsetParent属性返回一个对象的引用，这个对象是距离调用offsetParent的元素最近的（在包含层次中最靠近的），并且是已进行过CSS定位的容器元素。 如果这个容器元素未进行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（译注：IE和Opera除外），offsetParent属性 返回null。
句法：parentObj = element.offsetParent
变量：parentObj 是一个元素的引用，当前元素的偏移量在其中计算。