Validation Using JavaScript

<form role="form" method="post" id="the-form">
      <div class="col-md-12 padding-none">
       <div class="col-md-12 padding-none">
        <div class="col-sm-6">
         <div class="form-group">
          <label class="control-label">First Name*</label>
          <input maxlength="100" type="text" required="required" name="fname" class="form-control" id="RegFname">
          <span id="spnRegName" class="error_search">Please Enter First Name</span> </div>
        </div>
        <div class="col-sm-6">
         <div class="form-group">
          <label class="control-label">Last Name*</label>
          <input maxlength="100" type="text" required="required" class="form-control" name="lname" id="RegLname">
          <span id="spnRegLName" class="error_search">Please Enter First Name</span> </div>
        </div>
       </div>
       <div class="col-md-12 padding-none">
        <div class="col-sm-6">
         <div class="form-group">
          <label class="control-label">Email*</label>
          <input maxlength="100" type="text" required="required" class="form-control" name="user_email" id="RegEmail">
          <span id="spnRegEmil" class="error_search">Please Enter Email Address</span> </div>
        </div>
        <div class="col-sm-6">
         <div class="form-group">
          <label class="control-label">Password*</label>
          <input maxlength="100" type="password" required="required" class="form-control" psswd-shown="false" name="password" id="RegPwd">
          <span id="spnRegPwd" class="error_search">Please Enter Password</span> </div>
        </div>
       </div>
       <div class="col-md-12 padding-none">
        <div class="col-sm-12">
         <div class="form-group">
          <div class="check-newsletter">
           <label for="terms-check">
            <input name="terms" value="terms" id="terms-check" autocomplete="off" type="checkbox">
            <i></i> <span>Accept Terms and Conditions.*</span> </label>
           <br>
           <span id="spnRegTerms" class="error_search"></span> </div>
         </div>
        </div>
       </div>      
       <div class="clearfix"></div>
       <div class="col-md-12 padding-none">
        <div class="col-sm-12 text-right">
         <input name="action" type="hidden" value="the_ajax_hook">
         <button class="submit-btn" type="submit" id="test1" onclick="return fnStpOne()">Next</button>
        </div>
       </div>
      </div>
     </form>

//Onclick Validation

function fnStpOne() {
    document.getElementById("spnRegName").innerHTML = "";
    document.getElementById("spnRegLName").innerHTML = "";
    document.getElementById("spnRegEmil").innerHTML = "";
    document.getElementById("spnRegPwd").innerHTML = "";

    var flag = 0;
    var fname = document.getElementById("RegFname");
    var lname = document.getElementById("RegLname");
    var email = document.getElementById("RegEmail");
    var pwd = document.getElementById("RegPwd");

    if (fname != null) {
        var regExp = /^[a-zA-Z\s]+$/;
        var checkName = regExp.test(fname.value.trim());
        if (fname.value.trim() == "") {
            document.getElementById("spnRegName").innerHTML = "First Name is Required";
            flag = 1;
        } else if (checkName == false) {
            document.getElementById("spnRegName").innerHTML = "Please Enter a Correct First Name";
            flag = 1;
        }
    }
    if (lname != null) {
        var regExp = /^[a-zA-Z\s]+$/;
        var checkName = regExp.test(lname.value.trim());
        if (lname.value.trim() == "") {
            document.getElementById("spnRegLName").innerHTML = "Last Name is Required";
            flag = 1;
        } else if (checkName == false) {
            document.getElementById("spnRegLName").innerHTML = "Please Enter a Correct Last Name";
            flag = 1;
        }
    }
    if (email != null) {
        var regExp = /^[a-zA-Z0-9._+%-]+@[a-zA-Z0-9._]+\.[a-zA-Z]+$/;
        var check = regExp.test(email.value.trim());
        if (email.value.trim() == "") {
            document.getElementById("spnRegEmil").innerHTML = "Email is Required";
            flag = 1;
        } else if (check == false) {
            document.getElementById("spnRegEmil").innerHTML = "Please Enter a Correct Email Address";
            flag = 1;
        }
    }
    if (pwd != null) {
        if (pwd.value.trim() == "") {
            document.getElementById("spnRegPwd").innerHTML = "Password is Required";
            flag = 1;
        }
    }
    if (document.getElementById("terms-check").checked == false) {
        document.getElementById("spnRegTerms").innerHTML = "This is required field";
        flag = 1;
    }    
    if (flag == 1) {
        return false;
    } else {
        return true;
    }

}

//Onblur validation

jQuery(document).ready(function () {
        jQuery(".page-id-1963 .form-control").on("blur", function () {
            var txt_id = this.id;
            if (txt_id == "RegFname") {
                var objFname = document.getElementById("RegFname");
                document.getElementById("spnRegName").innerHTML = "";
                var regExp = /^[a-zA-Z\s]+$/;
                var check = regExp.test(objFname.value.trim());
                if (objFname.value.trim() == "") {
                    document.getElementById("spnRegName").innerHTML = "Please Enter First Name";
                } else if (check == false) {
                    document.getElementById("spnRegName").innerHTML = "Please Enter a Valid First Name";
                }
            }
            if (txt_id == "RegLname") {
                var objFname = document.getElementById("RegLname");
                document.getElementById("spnRegLName").innerHTML = "";
                var regExp = /^[a-zA-Z\s]+$/;
                var check = regExp.test(objFname.value.trim());
                if (objFname.value.trim() == "") {
                    document.getElementById("spnRegLName").innerHTML = "Please Enter First Name";
                } else if (check == false) {
                    document.getElementById("spnRegLName").innerHTML = "Please Enter a Valid First Name";
                }
            }
            if (txt_id == "RegEmail") {
                document.getElementById("spnRegEmil").innerHTML = "";
                var objFEmail = document.getElementById("RegEmail");
                var regExp = /^[a-zA-Z0-9._+%-]+@[a-zA-Z0-9._]+\.[a-zA-Z]+$/;
                var check = regExp.test(objFEmail.value.trim());
                if (objFEmail.value.trim() == "") {
                    document.getElementById("spnRegEmil").innerHTML = "Please Enter Email Address";
                } else if (check == false) {
                    document.getElementById("spnRegEmil").innerHTML = "Please Enter a Correct Email Address";
                }
            }
            if (txt_id == "RegPwd") {
                var objPass = document.getElementById("RegPwd");
                document.getElementById("spnRegPwd").innerHTML = "";
                if (objPass.value.trim() == "") {
                    document.getElementById("spnRegPwd").innerHTML = "Please Enter Password";
                }
            }

        });

    });