Sharepoint Forms Controls Validation Using JQuery

1.Add bellow script after <asp:Content ContentPlaceHolderId="PlaceHolderMain" runat="server"> 
 
 <script type="text/javascript" src="../../SiteAssets/jquery-1.8.2.min.js"></script >
 <script type="text/javascript" src="../../SiteAssets/jquery.SPServices-2014.01.min.js">  </script> 
 <script type="text/javascript">

Single Line Text Box:

  var DueDate=$("input[title='Due Date']").val();
        if(typeof(DueDate) == "undefined" || DueDate== null || DueDate=="")
         {
               alert("Please Enter Due Date.");
               $("input[title='Due Date']").focus();
                 return false;
           }
   Note : Here  Due Date is List Column Name                

Muti Line Text Box with Plain Text:

var Name =$("textarea[title='Name']").val();
    if( Name=="")
    {
     alert("enter Name");
    $("textarea[title='Name']").focus();
     return false;
   }


Muti Line Text Box With Rich Text:

 if($('#tdDetails div[role=textbox]').text().length<=1)
    {
       alert("Please Enter Details.");                        
        return false;
   }

Here control is present in  the tdDetails is TD id of table.

Drodown List:

 var LocationId= $("select[Title='Location']").attr("id");
 var LocationControl= document.getElementById(LocationId);                 
 var  strLocation= LocationControl.options[LocationControl.selectedIndex].text;
 if(strLocation=="(None)")
  {
        alert("Please select the Location value");
         return false;
   }