<Script>
                
                function getFocus(obj) {
                     obj.style.color='red';
                     obj.style.background='#DBDBDB';
                }
                function getBlur(obj) {
                     obj.style.color='black';
                     obj.style.background='white';
                }
                </Script>
                <BODY onLoad=document.form1.name.focus()>
                <FORM NAME="form1">
                姓  名:<INPUT TYPE="text" NAME="name"
                onFocus=getFocus(this) onBlur=getBlur(this)><BR>
                电  话:<INPUT TYPE="text" NAME="tel"
                onFocus=getFocus(this) onBlur=getBlur(this)><BR>
                </FORM>
                </BODY>
                
                
                <Script>
                
                var i = 0;
                function movenext(obj,i) {
                if(obj.value.length==4){
                     document.forms[0].elements[i+1].focus();
                }
                }
                function result() {
                fm = document.forms[0];
                num = fm.elements[0].value + 
                fm.elements[1].value +
                fm.elements[2].value + 
                fm.elements[3].value ;
                alert("你输入的信用卡号码是"+ num);
                }
                </Script>
                <BODY onLoad=document.forms[0].elements[i].focus()>
                请输入你的信用卡号码:
                <form>
                <input type=text size=3 maxlength=4 onKeyup=movenext(this,0)> -
                <input type=text size=3 maxlength=4 onKeyup=movenext(this,1)> -
                <input type=text size=3 maxlength=4 onKeyup=movenext(this,2)> -
                <input type=text size=3 maxlength=4 onKeyup=movenext(this,3)>
                <input type=button value=显示 onClick=result()>
                </form>
                </BODY>