不提交

document.onkeydown = function(event) {   
            var target, code, tag;   
            if (!event) {   
                event = window.event; //针对ie浏览器   
                target = event.srcElement;   
                code = event.keyCode;   
                if (code == 13) {   
                    tag = target.tagName;   
                    if (tag == "TEXTAREA") { return true; }   
                    else { return false; }   
                }   
            }   
            else {   
                target = event.target; //针对遵循w3c标准的浏览器，如Firefox   
                code = event.keyCode;   
                if (code == 13) {   
                    tag = target.tagName;   
                    if (tag == "INPUT") { return false; }   
                    else { return true; }    
                }   
            }   
        };