11.2.5 atan2方法.html

javascript即用即差核心对象手册

<form>
   X＝<input type="text" name="x" size="4"/>
   Y＝<input type="text" name="y" size="4"/>
   <input type="button" value="计算" onclick="Cal()"/>
   <div id="result"></div>
</form>
<script>
 function Cal()
 {
   with (Math )
    {
      var x=document.forms[0].x.value;
      var y=document.forms[0].y.value;
      var str="atan2("+x+","+y+")="+atan2(y,x)+"<br>";
      str+="atan("+y+"/"+x+")="+atan(y/x);
      document.getElementById("result").innerHTML=str;
    }
  }
</script>