<label for="Username">Username:</label>
 <input type="text" id="txtUserName" placeholder="Enter UserName"/>
 <label for="Password">Password</label>
 <input type="text" id="txtPass" placeholder="Enter Password" />
 <input type="button" onclick="loginc()" value="Click Me" />

function loginc() {
var username = document.getElementById("txtUserName").value;
if (username == "") {
    alert("Please enter the valid name");
    return false;
}

var password = document.getElementById("txtPass").value;
if (password == "") {
    alert("Please enter valid password");
}
var urlink = "http://192.168.0.102:97/Service1.svc/getlogin";

var datat = { Username: "username", Password: "password" };



    $.ajax({
        type: 'POST',
        url: urlink,
        dataType: "json",
        contentType: "application/x-www-form-urlencoded; charset=UTF-8",

        data:datat,

        success: function (resp) {
            alert(resp);
            if (resp.length != 0) {
                alert("Logged On");
            } else {
                alert("Wrong Credentials");
            }

        },
        error: function (e) {

            alert("Invalid");

        }
    });