javascript - 根据 'false' 检查属性时出错

Question

我使用这个 JavaScript 语法来验证复选框...

 alert(document.getElementById("ctl00_ContentPlaceHolder1_Chkreg").checked);
  if (document.getElementById("ctl00_ContentPlaceHolder1_Chkreg").checked == false) {
        document.getElementById("ctl00_ContentPlaceHolder1_ErrorMsg").innerHTML = "please select the checkbox";
        document.getElementById("ctl00_ContentPlaceHolder1_Chkreg").focus();
        return false;
    }

我的警报显示错误，但我的 if 循环不起作用...任何建议...

Answer 1

假设你的框没有被选中，我个人会这样写:

var box = document.getElementById("ctl00_ContentPlaceHolder1_Chkreg");
if (!box.checked) {
    document.getElementById("ctl00_ContentPlaceHolder1_ErrorMsg").innerHTML = "please select the checkbox";
    box.focus();
    return false;
}