不能以上面说明的方式调用PHP函数。但是，您可以使用AJAX调用PHP脚本，代码如下所示。您也可以在这里找到一个简单的示例。让我知道您是否需要进一步澄清

使用jQuery

<script type="text/javascript" src="./jquery-1.4.2.js"></script>
<script type="text/javascript">
function compute() {
    var params="session=123";
    $.post('myphpscript.php',params,function(data){ 
            alert(data);//for testing if data is being fetched
            var myObject = eval('(' + data + ')');
            document.getElementById("result").value=myObject(addend_1,addend_2);
        }); 
}
</script>

准系统Javascript替代

   <script type="text/javascript">

    function compute() {
        var params="session=123"
        var xmlHttp; 
        var addend_1=document.getElementById("par_1").value;
        var addend_2=document.getElementById("par_2").value;

        try 
        { 
            xmlHttp = new XMLHttpRequest(); 
        } 
        catch (e) 
        { 
            try 
            { 
                xmlHttp = new ActiveXObject("Msxml2.XMLHTTP"); 
            } 
            catch (e) 
            { 
                try 
                { 
                    xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); 
                } 
                catch (e) 
                { 
                    alert("No Ajax for YOU!"); 
                    return false; 
                } 
            } 
        } 
        xmlHttp.onreadystatechange = function() 
        { 
            if (xmlHttp.readyState == 4) { 
                ret_value=xmlHttp.responseText;
                var myObject = eval('(' + ret_value + ')');
                document.getElementById("result").value=myObject(addend_1,addend_2);
            }
        }       
        xmlHttp.open("POST", "http://yoururl/getjs.php", true);
        xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
        xmlHttp.setRequestHeader("Content-length", params.length);
        xmlHttp.setRequestHeader("Connection", "close");
        xmlHttp.send(params);
    }
    </script>