使用js实现两点之间距离计算功能

<script language="JavaScript">
<!--
function juli(form) {       // 从form的表单中分别提取两个点的横、纵坐标
var x1 = eval(form.x1.value);   // 第一个点的横坐标
var y1 = eval(form.y1.value);   // 第一个点的纵坐标
var x2 = eval(form.x2.value);   // 第二个点的横坐标
var y2 = eval(form.y2.value);   // 第二个点的纵坐标
var xdiff = x2 - x1;            // 计算两个点的横坐标之差
var ydiff = y2 - y1;            // 计算两个点的纵坐标之差
form.answer.value = Math.pow((xdiff * xdiff + ydiff * ydiff), 0.5);   // 计算两点之间的距离，并将结果返回表单元素
}
function IEMouseMove() {
document.test.x.value = window.event.x;
document.test.y.value = window.event.y;
document.onmousemove= IEMouseMove;
}
//-->
</script>
<center>
<form name=test  onMousemove="IEMouseMove()">
<table border=0 cellspacing=2 cellpadding=5>
<tr>
<td colspan=4 align=center>计算平面两点之间的距离</td>
</tr>
<tr>
<td colspan=2 align=center>A点</td>
<td colspan=2 align=center>B点</td>
</tr>
<tr>
<td align=center>A点横坐标</td>
<td align=center>A点纵坐标</td>
<td align=center>B点横坐标</td>
<td align=center>B点纵坐标</td>
</tr>
<tr>
<td align=center><input type=text name=x1 size=5></td>
<td align=center><input type=text name=y1 size=5></td>
<td align=center><input type=text name=x2 size=5></td>
<td align=center><input type=text name=y2 size=5></td>
</tr>
<tr>
<td colspan=4 align=center><input type=button value="计算距离" onClick="juli(this.form)"></td>
</tr>
<tr>
<td colspan=4 align=center>X:<input type=text name=x size=5>&nbsp;Y:<input type=text name=y size=5>&nbsp;<input type=text name=answer size=20></td>
</tr>
</table>
</form>
</center>