将类似于 info 格式转化为 info2 

    var info = {
      id: 1,
      id1: 2,
      userName1: '刘玄德',
      userName2: '刘玄德',
      userName3: '大哥',
      userAge: 45,
      userAge1: 46,
      userAge2: 47
    }

    var info2 = {
      id: 1,
      id_1: 2,
      user_name_1: '刘玄德',
      user_name_2: '刘玄德',
      user_name_3: '刘玄德',
      user_age: 45,
      user_age_1: 46,
      user_age_2: 47
    }

下属两种解决方案：可谓相当潇洒的答案，一行搞定

// segmentDefault回答者 asseek 的答案： 
const toLine = hump => hump.replace(/([A-Z]|\d)/g, (a, l) => `_${l.toLowerCase()}`);

var info = {
  id: 1,
  id1: 2,
  userName1: '刘玄德',
  userName2: '刘玄德',
  userName3: '大哥',
  userAge: 45,
  userAge1: 46,
  userAge2: 47
};
var newObj = {}
for (let k in info) {
  newObj[toLine(k)] = info[k]
}
console.log(newObj)

本人的答案，想了很久，asseek 的答案可谓是天上飞，我的答案就是地上爬了

<script>
    var info = {
      id: 1,
      id1: 2,
      userName1: '刘玄德',
      userName2: '刘玄德',
      userName3: '大哥',
      userAge: 45,
      userAge1: 46,
      userAge2: 47
    }

    var info2 = {
      id: 1,
      id_1: 2,
      user_name_1: '刘玄德',
      user_name_2: '刘玄德',
      user_name_3: '刘玄德',
      user_age: 45,
      user_age_1: 46,
      user_age_2: 47
    }

    function copy(obj){//用于复制一个对象
      var newobj = {};
      for ( var attr in obj) {
          newobj[attr] = obj[attr];
      }
      return newobj;
    }
    var changeObj = function (obj) {
      var copyobj = copy(obj)
      var regNum = new RegExp(/\d/)
      var regStr = new RegExp(/[A-Z]/g)
      var arr = Object.keys(obj);

      var newObj = {}
      arr.forEach((k, index) => {
        var kArr = k.split('')
        var newK = ''
        kArr.forEach((item,index)=>{
          if(regNum.test(item)){
            kArr[index] = "_" + item
          }
          if(regStr.test(item)){
            kArr[index] = "_" + item.toLowerCase()
          }
        })
        newKey = kArr.join('')
        newObj[newKey] = obj[k]
        console.log(newKey)
        
      })
      console.log(newObj)
      return newObj
    }
    changeObj(info)
  </script>

 

jQuery.validator.addMethod("alnum", function(value, element) {
return this.optional(element) || /^[a-zA-Z0-9_]+$/.test(value);
}, "只能包括英文字母数字下划线");

$("#form1").validate({
rules:{
adminName:{
required: true,
minlength: 2,
maxlength: 10
},
realname:{
required: true,
stringCheck: true
},
pwd:{
required: true,
minlength: 8,
maxlength: 20,
alnum:true
}
},
messages:{
adminName:{
required: "请填写用户名",
minlength:"用户名最少为2个字符",
maxlength:"用户名最长为10个字符"
},
realname:{
required: "请填写姓名",
stringCheck: "请正确输入姓名"
},
pwd:{
required:"请填写密码",
minlength:"密码最少为8个字符",
maxlength:"密码最多为20个字符",
alnum:"只能包括英文字母数字下划线"
}
},
submitHandler:function(form){
       //在Submit之前，且所有驗證成功。
       $("#password-md5").val(hex_md5($("#password").val()));
prepareConfirm();
showLayer('lightBox-1');
       return false;
    }

});

   
   <tr>

  <td>初始密码：</td><td><input type="text" class="search_txt" name="pwd" id="password" οncοpy="return false" οnpaste="return false"/>
    <input type="hidden" class="search_txt" name="password" id="password-md5"/></td>
   </tr>