代码如下：
<SCRIPT LANGUAGE="JavaScript"> <!-- Begin function distance(form) { var x1 = eval(form.x1.value); var y1 = eval(form.y1.value); var x2 = eval(form.x2.value); var y2 = eval(form.y2.value); var xdiff = x2 - x1; var ydiff = y2 - y1; form.answer.value = Math.pow((xdiff * xdiff + ydiff * ydiff), 0.5); } // End --> </script> <center> <form> <table border=3 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="distance(this.form)"></td> </tr> <tr> <td colspan=4 align=center><input type=text name=answer size=20></td> </tr> </table> </form> </center>