Check UserName availability by using AJAX in asp.net - asp.net

Question

I'm creating a SignUp form,i want to add a feature to the form in which whenever a new user types an username in the text box, it should automatically check if the username is already taken or not(should compare it with usernames exist in SQL server database). I want to implement this feature using AJAX.

Answer 1

Use the following jquery code, don't forget include jquery libraries
$("#<%=txtJournalIdToMove.ClientID %>").blur(function () {
var journalTextBoxId = '<%= this.txtJournalIdToMove.ClientID %>';
var journalId = $("#" + journalTextBoxId).val();
var params = '{"JournalId":"' + journalId + '"}';
$.ajax({
type: "POST",
url: "Default.aspx/PopulateVolumeNo",
data: params,
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function (data) {
// Replace the div's content with the page method's return.
var returnValue = data.d;
if (returnValue == null) {
alert("The given journal id does not exist or is in active in db.");
}
else {
//If success do your functionality
});
}
}
});
});

Answer 2

Try this onchange or on blur event of a textbox. Here I used user-name-box as text box id
$.post('/Server/CheckAvailablity/',
{name:function(){return $('#user-name-box').val()},
function(response){
if(response.status="Y"){
alert('available');
}
else{
alert('not available');
}
}
);
In server side CheckAvailablity method prepare a JSON object like {"status":"Y"} and return