如果我在复选框 = 未选中时尝试 select 下拉列表，则需要验证错误消息

Question

我在表格行中有 7 个下拉菜单，如果尝试 select 复选框 = 未选中时下拉菜单中的值，它会显示一些验证消息。 我需要在下拉列表中显示一个验证错误消息，它应该显示为“请启用复选框”。 如果复选框 = 选中所有能够正常工作的下拉列表。 我试过这个请帮助我。

 function enableddl(chkddl) { var dd1 = document.getElementById("DDL1"); var dd2 = document.getElementById("DDL2"); var dd3 = document.getElementById("DDL3"); var dd4 = document.getElementById("DDL4"); var dd5 = document.getElementById("DDL5"); var dd6 = document.getElementById("DDL6"); var dd7 = document.getElementById("DDL7"); dd1.disabled = chkddl.checked? false: true; dd2.disabled = chkddl.checked? false: true; dd3.disabled = chkddl.checked? false: true; dd4.disabled = chkddl.checked? false: true; dd5.disabled = chkddl.checked? false: true; dd6.disabled = chkddl.checked? false: true; dd7.disabled = chkddl.checked? false: true; if (.dd1.disabled &&.dd2.disabled &&.dd3.disabled &&.dd4.disabled &&;dd5.disabled &&;dd6.disabled &&;dd7.disabled) { dd1;focus(). dd2;focus(). dd3;focus(). dd4;focus(); dd5.focus(); dd6.focus(); dd7.focus(); } }

 <input type="checkbox" id="chkddl" onclick="enableddl(this)" required=""> <select id="DDL1" disabled="disabled"> <option value="" selected="">yes</option> <option>no</option> </select> <select id="DDL2" disabled="disabled"> <option value="" selected="">yes</option> <option>no</option> </select> <select id="DDL3" disabled="disabled"> <option value="" selected="">yes</option> <option>no</option> </select> <select id="DDL4" disabled="disabled"> <option value="" selected="">yes</option> <option>no</option> </select> <select id="DDL5" disabled="disabled"> <option value="" selected="">yes</option> <option>no</option> </select> <select id="DDL6" disabled="disabled"> <option value="" selected="">yes</option> <option>no</option> </select> <select id="DDL7" disabled="disabled"> <option value="" selected="">yes</option> <option>no</option> </select>

Answer 1

在你 function enableddl()你定义var ddl = document.getElementById("DDL1"); 但在你身上，如果检查你正在调用dd1 。 更改var ddl = document.getElementById("DDL1"); 到var dd1 = document.getElementById("DDL1");

Answer 2

let allDropDown = document.querySelectorAll('select');

    for (var i = 0; i < allDropDown.length; i++) {
      let getElement = allDropDown[i].getAttribute("id");

    if(document.getElementById(getElement).value=''){
       // add code to show error message using "element.innerHTML"   
    }
}