禁用Enter键表单自动提交实现代码

//禁用Enter键表单自动提交
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; }
}
}
};