javascript 数字验证

        function CheckData() {
            //验证输入框中的是否是数字
            var theValue1 = document.getElementById("textfield").value;
            for (var i = 0; i < theValue1.length; i++) {
                if (parseInt(theValue1.charCodeAt(i)) < 48 || parseInt(theValue1.charCodeAt(i)) > 57) {
                    alert("库存数量只能输入整数！");
                    document.getElementById("TextBox2").value = "";
                    return;
                }
                if (theValue1.length > 10) {
                    alert("库存数量只能输入10位以下的整数！");
                    document.getElementById("TextBox2").value = "";
                    return;                   
                }    
            }
            var theValue2 = document.getElementById("textfield3").value;
            for (var i = 0; i < theValue2.length; i++) {
                if (parseInt(theValue2.charCodeAt(i)) < 48 || parseInt(theValue2.charCodeAt(i)) > 57) {
                    alert("库存数量只能输入整数！");
                    document.getElementById("TextBox3").value = "";
                    return;
                }
                if (theValue2.length > 10) {
                    alert("库存数量只能输入10位以下的整数！");
                    document.getElementById("TextBox3").value = "";
                    return;
                }   
            }