!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
html xmlns="http://www.w3.org/1999/xhtml">
head>
  title>/title>
  script type="text/javascript">
    function validation() {
      var val = document.getElementById("txtNumber").value;
      var regu = /^(\-|\+)?\d+(\.\d+)?$/;
      if (val != "") {
        if (!regu.test(val)) {
          document.getElementById("labResult").style.color = "red";
          document.getElementById("labResult").innerHTML = "验证失败！";
        } else {
          document.getElementById("labResult").style.color = "green";
          document.getElementById("labResult").innerHTML = "验证成功！";
        }
      }
    }
  /script>
/head>
body>
  input id="txtNumber" name="txtNumber" type="text" />
  input id="btnValidation" name="btnValidation" type="button" value="校验" onclick="validation()" />
  验证结果：label id="labResult" >/label>
/body>
/html>