写了一个表单验证函数，看完包你会用，有演示。

Question

必要的工具函数：
  var _$ = function(n, w) {
    return typeof n == "string" ? (w || window).document.getElementById(n) : n;
  };  var _ergodicElement = function(n, f, w) {
    var e = _$(n, w);
    if(e.nodeType == 1 && !e.getAttribute("noergodic")) {
      f(e);
    }
    for(var n = e.firstChild; n; n = n.nextSibling) {
      _ergodicElement(n, f, w);
    }
  };  var _attachEvent = function(n, e, w) {
    if(document.addEventListener) {
      for(var i in e) {
        _$(n, w).addEventListener(i, e[i], false);
      }
    } else if(document.attachEvent) {
      for(var i in e) {
        _$(n, w).attachEvent("on" + i, e[i]);
      }
    }
  };  var _detachEvent = function(n, e, w) {
    if(document.removeEventListener) {
      for(var i in e) {
        _$(n, w).removeEventListener(i, e[i], false);
      }
    } else if(document.detachEvent) {
      for(var i in e) {
        _$(n, w).detachEvent("on" + i, e[i]);
      }
    }
  };  var _rewriteAccess = function(a, f) {
    if(a.constructor == String) {
      var d = {};
      var r = /(\w+?)(?:=)([^\s;]+)/g;
      while(r.exec(a)) {
        d[RegExp.$1] = f && f[RegExp.$1] ? f[RegExp.$1](decodeURIComponent(RegExp.$2)) : decodeURIComponent(RegExp.$2);
      }
      return d;
    }
    if(a.constructor == Object) {
      var d = "";
      for(var i in a) {
        d += i + "=" + encodeURIComponent(f && f[i] ? f[i](a[i]) : a[i]) + "; ";
      }
      return d;
    }
  };  var _rewriteObject = function(a, b) {
    for(var i in b) {
      if(!a[i]) {
        a[i] = b[i];
      }
    }
  };

Answer 1

验证函数【上】:
  (function() {
    //函数盒子
    var _bin = function(form, request) {
      try {
        //定义验证队列
        var verifyArray = [];        //定义验证函数
        var verify = function(t) {
          if(/checkbox|radio/i.test(t.type)) {            //定义对比队列
            t = t.name ? document.getElementsByName(t.name) : {0 : t, length : 1};            //执行对比队列
            for(var i = 0; i < t.length; i++) {
              if(t[i].checked) {
                t[0].verifyStatus = "right";
                break;
              }
              if(i == t.length - 1) {
                t[0].verifyStatus = "empty";
              }
            }            //执行描述函数
            return depict(t[0]);          } else {            //定义对比参数
            var v = t.value;
            var r = t.getAttribute("regexp");
            var e = t.getAttribute("equate");
            var m = t.getAttribute("method");            //清除对比参数
            t.removeAttribute("depictmethod");            //执行对比参数
            if(!v) {
              t.getAttribute("nullable") ? t.verifyStatus = "blank" : t.verifyStatus = "empty";
            } else if(r && (v.search(r) < 0)) {
              t.verifyStatus = "error";
            } else if(e && (v != _$(e).value)) {
              t.verifyStatus = "error";
            } else if(m && (m = request[m](v, t))) {
              t.verifyStatus = "error";
              t.setAttribute("depictmethod", m);
            } else {
              t.verifyStatus = "right";
            }            //执行描述函数
            return depict(t);          }
        };        //定义描述函数
        var depict = function(t) {          //定义描述参数
          var s = t.verifyStatus;
          var d = t.getAttribute("depictmethod") || _rewriteAccess(t.getAttribute("depict") || "")[s] || "";          //定义描述节点
          if(t.depictNode === undefined) {
            t.depictNode = null;
            if(t.getAttribute("for")) {
              t.depictNode = _$(t.getAttribute("for"));
            } else {
              _ergodicElement(t.parentNode, function(e) {
                if(e.getAttribute("depictnode") && e.getAttribute("depictnode") == "depictnode") {
                  t.depictNode = e;
                  return;
                }
              });
            }
          }          //执行描述
          if(t.depictNode) {
            if(!t.depictNodeInner) {
              t.depictNodeInner = t.depictNode.innerHTML;
            }
            t.depictNode.innerHTML = "<span class=\"" + s + "\">" + d + "<\/span>";
          } else if(/input|empty|error/i.test(s)) {
            return d;
          }        };        //定义提交函数
        var submit = function() {          //定义提交参数
          var m = [];
          var c = 0;          //执行对比队列
          for(var i = 0; i < verifyArray.length; i++) {
            if(/checkbox|radio/i.test(verifyArray[i].type) && verifyArray[i].name && document.getElementsByName(verifyArray[i].name)[0] != verifyArray[i]) {
              continue;
            }
            if(d = verify(verifyArray[i])) {
              m.push(d);
            }
            if(/input|empty|error/i.test(verifyArray[i].verifyStatus)) {
              c++;
            }
          }          //执行提交校对
          if(request["submit"]) {
            if(d = request["submit"](verifyArray, c)) {
              m.push(d);
              c++;
            }
          }          //执行描述函数
          if(c) {
            alert("您提交的表单中有 " + c + " 处错误，请更正后再提交！" + (m.length ? "\n\n您可能需要确认以下内容：\n\n※ " + m.join("\n※ ") : ""));
          }          //返回对比结果
          return c;        };        //定义锁定函数
        var locked = function() {
          for(var i = 0; i < verifyArray.length; i++) {
            try {
              verifyArray[i].setAttribute("readonly", "readonly", 0);
            } catch(error) {
              continue;
            }
          }
        };        //定义行为函数
        var action = function() {
          var a = arguments[0].toLowerCase();
          var e = _$(arguments[1]);          switch(a) {            //覆载
            case "afresh" : {
              _ergodicElement(form, function(e) {
                action("append", e);
              });
              break;
            }            //撤消
            case "repeal" : {
              _ergodicElement(form, function(e) {
                action("remove", e);
              });
              break;
            }            //附加
            case "append" : {
              if(!e.verifyReady) {
                if(/text|testarea|password|hidden/i.test(e.type || e.tagName) && (e.getAttribute("regexp") || e.getAttribute("equate") || e.getAttribute("method"))) {                  //定义事件函数
                  if(!e.verifyFocus) {
                    e.verifyFocus = function() {
                      if(/blank|empty|undefined/i.test(e.verifyStatus)) {
                        e.verifyStatus = "input";
                      }
                      depict(e);
                    };
                    e.verifyBlur = function() {
                      verify(e);
                    };
                  }                  //注册事件函数
                  _attachEvent(e, {
                    "focus" : e.verifyFocus,
                    "blur"  : e.verifyBlur
                  });                  //注册验证对象
                  verifyArray.push(e);                  //设置验证标记
                  e.verifyReady = "complete";                } else if(/select/i.test(e.tagName) && (e.getAttribute("regexp") || e.getAttribute("equate") || e.getAttribute("method"))) {                  //定义事件函数
                  if(!e.verifyChange) {
                    e.verifyChange = function() {
                      verify(e);
                    };
                  }                  //注册事件函数
                  _attachEvent(e, {
                    "change" : e.verifyChange
                  });                  //注册验证对象
                  verifyArray.push(e);                  //设置验证标记
                  e.verifyReady = "complete";                } else if(/checkbox|radio/i.test(e.type) && !e.getAttribute("nullable")) {                  //定义事件函数
                  if(!e.verifyClick) {
                    e.verifyClick = function() {
                      verify(e);
                    };
                  }                  //注册事件函数
                  _attachEvent(e, {
                    "click" : e.verifyClick
                  });                  //注册验证对象
                  verifyArray.push(e);                  //设置验证标记
                  e.verifyReady = "complete";                } else if(e.getAttribute("request")) {                  //定义事件函数
                  if(!e.verifyClick) {
                    e.verifyClick = function() {
                      request[e.getAttribute("request")]();
                    };
                  }                  //注册事件函数
                  _attachEvent(e, {
                    "click" : e.verifyClick
                  });                  //设置验证标记
                  e.verifyReady = "complete";                }
              }
              break;
            }

Answer 2

验证函数【下】:
            //移除
            case "remove" : {
              if(e.verifyReady) {
                if(/text|testarea|password|hidden/i.test(e.type || e.tagName) && (e.getAttribute("regexp") || e.getAttribute("equate") || e.getAttribute("method"))) {                  //分离描述内容
                  if(e.depictNodeInner) {
                    e.depictNode.innerHTML = e.depictNodeInner;
                  }                  //分离事件函数
                  _detachEvent(e, {
                    "focus" : e.verifyFocus,
                    "blur"  : e.verifyBlur
                  });                  //分离验证对象
                  for(var i in verifyArray) {
                    if(verifyArray[i] == e) {
                      verifyArray.splice(i, 1);
                    }
                  }                  //删除验证标记
                  delete e.verifyReady;                } else if(/select/i.test(e.tagName) && (e.getAttribute("regexp") || e.getAttribute("equate") || e.getAttribute("method"))) {                  //分离描述内容
                  if(e.depictNodeInner) {
                    e.depictNode.innerHTML = e.depictNodeInner;
                  }                  //分离事件函数
                  _detachEvent(e, {
                    "change" : e.verifyChange
                  });                  //分离验证对象
                  for(var i in verifyArray) {
                    if(verifyArray[i] == e) {
                      verifyArray.splice(i, 1);
                    }
                  }                  //删除验证标记
                  delete e.verifyReady;                } else if(/checkbox|radio/i.test(e.type) && !e.getAttribute("nullable")) {                  //分离描述内容
                  if(e.depictNodeInner) {
                    e.depictNode.innerHTML = e.depictNodeInner;
                  }                  //分离事件函数
                  _detachEvent(e, {
                    "click" : e.verifyClick
                  });                  //分离验证对象
                  for(var i in verifyArray) {
                    if(verifyArray[i] == e) {
                      verifyArray.splice(i, 1);
                    }
                  }                  //删除验证标记
                  delete e.verifyReady;                } else if(e.getAttribute("request")) {                  //分离事件函数
                  _detachEvent(e, {
                    "click" : e.verifyClick
                  });                  //删除验证标记
                  delete e.verifyReady;                }
              }
              break;
            }          }
        };        //初始化表单
        form = _$(form);
        form.setAttribute("onsubmit", "return false", 0);        //初始化请求
        request = request || {};
        _rewriteObject(request, {
          "onsubmit" : function() {
            if(!submit() && !locked()) {
              submit = null;
              form.submit();
            }
          },
          "onreset" : function() {
            if(confirm("重置操作将清空信息，确认重置？")) {
              form.reset();
              for(var i = 0; i < verifyArray.length; i++) {
                if(verifyArray[i].depictNode) {
                  verifyArray[i].depictNode.innerHTML = verifyArray[i].depictNodeInner;
                }
              }
            }
          },
          "onsaveas" : function() {
            if(!submit() && confirm("保存操作将更新信息，确认保存？") && !locked()) {
              submit = null;
              form.submit();
            }
          },
          "oncancel" : function() {
            throw new Error("Developing...");
          }
        });        //初始化行为
        action("afresh");        return function() {action(arguments[0], arguments[1])};
      } catch(error) {      }
    };    //添加全局引用
    verify = _bin;
  })();
说明 + 演示地址：http://www.izhaoyang.com/temp/index.htm

Answer 3

更新了下，演示地址：http://www.zhanghong.name/example/verify/