请高手帮我在这段代码里加上,网页防刷新

<HTML>  
 <HEAD>  
  <TITLE> 计算器 </TITLE>  
  <META NAME="Generator" CONTENT="EditPlus">  
  <META NAME="Author" CONTENT="">  
  <META NAME="Keywords" CONTENT="">  
  <META NAME="Description" CONTENT="">  
<SCRIPT LANGUAGE="JavaScript">  
<!--   
    var result = "";   
    var view  ;   
    var count = 1;   
    var equal;   
       
    function addNum(num){   
        view = document.getElementById("view");        
        equal = document.getElementById("equal");   
  
        if(count % 2 == 0){   
            result = "";   
            view.setAttribute("value","0");   
            count = 1;   
        }    
           
        resultresult = result+""+num;   
           
        view.setAttribute("value",result);   
  
        equal.focus();   
    }   
  
    function getResult(){   
        if(view!=null){   
            resultresult = result+" = "+eval(result);   
            view.setAttribute("value",result);   
            count++;   
        }   
           
    }   
      
    function onkeypress()   
    {   
        if ( event.keyCode=='13' )   
        {   
            getResult();   
        }   
    }   
//-->  
</SCRIPT>  
    
  
 <style>  
    input {   
        height:30px;   
        width:60px;   
    }   
 </style>  
 </HEAD>  
  
 <BODY>  
    <table align="center" width="30%" style="border-left:2px solid #000;border-top:2px solid #000;border-right:2px solid #000;border-bottom:2px solid #000;">  
        <tr>  
            <td colspan="6" bgcolor="#000099" height="30px" align="center">  
                <font color="#ffffff"><b>计算器</b></font>  
            </td>    
        <tr>  
        <tr>  
            <td colspan="4">  
                <input id="view" size="60" style="width:460px;text-align:right;" value="0"/>  
            </td>  
            <td >  
                <input id="equal" type="button" value="=" onclick="getResult();"/>  
            </td>  
        <tr>  
        <tr>  
            <td>  
                <input id="1" type="button" value="1" onclick="addNum(1);"/>  
            </td>  
            <td>  
                <input id="2" type="button" value="2" onclick="addNum(2);"/>  
            </td>  
            <td>  
                <input id="3" type="button" value="3" onclick="addNum(3);"/>  
            </td>  
            <td>  
                <input id="4" type="button" value="4" onclick="addNum(4);"/>  
            </td>  
            <td>  
                <input id="+" type="button" value="+" onclick="addNum('+');"/>  
            </td>  
        <tr><tr>  
            <td>  
                <input id="5" type="button" value="5" onclick="addNum(5);"/>  
            </td>    
            <td>  
                <input id="6" type="button" value="6" onclick="addNum(6);"/>  
            </td>  
            <td>  
                <input id="7" type="button" value="7" onclick="addNum(7);"/>  
            </td>  
            <td>  
                <input id="8" type="button" value="8" onclick="addNum(8);"/>  
            </td>  
            <td>  
                <input id="-" type="button" value="-" onclick="addNum('-');"/>  
            </td>  
        <tr><tr>    
            <td>  
                <input id="9" type="button" value="9" onclick="addNum(9);"/>  
            </td>  
            <td>  
                <input id="0" type="button" value="0" onclick="addNum(0);"/>  
            </td>  
            <td>  
                <input id="dot" type="button" value="." onclick="addNum('.');"/>  
            </td>  
            <td>  
                <input id="/" type="button" value="/" onclick="addNum('/');"/>  
            </td>  
            <td>  
                <input id="*" type="button" value="*" onclick="addNum('*');"/>  
            </td>  
        <tr>    
    </table>  
 </BODY>  
</HTML>