I am trying to implement a sign-up form that asks users to input the desired login-id. The user inputs the desired login-id into a text box.
I would like to perform validation on this text box to see if the desired login-id is available without having to submit the form.
The validation should start happening say after the 5th character is input into the text box.
You should validate the complete username typed in. This will reduce your client server interaction too thus giving you performance too.
You can use jQuery's ajax method. Which will call your server side code and you can check from there by querying the database and can send back the date to client side.
HTML:
<input type="text" id="username" onblur="checkUsername(this);"/>
Javascript:
function checkUsername(element){
$.ajax({
url: server_url,
data : element.value
}).done(function(data) { //json object returned from server
if(data.true){
//allowed
}else{
alert("select another username");
}
});
}
You can use the Client Side Validation module. This module does the validation and shows the error message before the submission of the form
