<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>

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！";

    }

  }

}