Home/ Questions/Q 8927133
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-06-15T08:08:59+00:00

I have a small jQuery/AJAX script that checks if a username is already in

  • 0

I have a small jQuery/AJAX script that checks if a username is already in use or not. It queries a PHP script, which in turn outputs the number of users with the specified username. I have an error counter that keeps track of the number of validation errors on the form, and I increment the counter if the username is already in use.

//Keep track of number of errors
 var errors = 0;
 //Keep track of error messages
 var errorMsg = "";

//Check if the passwords match (this part works as expected)
 if($("#password").val() != $("#repeat").val()) {
     errors++;
     errorMsg += "<li>Passwords do not match!</li>";
 }

     //Now check if the user exists
     var userName = $("#user").val();
    $.ajax({   
        type: "POST",
        data : {'user': userName},
        cache: false,  
        url: "js/ajax/addUser.php?action=checkuser",   
        success: function(data){
            var result = parseInt(data);
            //For debugging purposes
            alert("Before checking the data, # of errors is: " + errors);
            if(result > 0) {
                errors++;
                errorMsg += "<li>A user with the name <strong>" + userName + "</strong> already exists!</li>";
            }
            //For debugging purposes
            alert("After checking the data, # of errors is: " + errors);

        }
    });
    //For debugging purposes
    alert("Before validating the form, # of errors is: " + errors);

     if(errors > 0) {
         //Output error message
     }
     else {
         //Send the form
     }

As mentioned in the comments, I have a few alert()‘s for debugging. The first two (within the AJAX request) display the correct amount of errors. However, when I get to the third one, it completely disregards any errors that occurred within the AJAX request.

I have trimmed my code down to just the essentials, but if the error is not clear within the snippet provided, I can post the entire thing.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    ajax is asynchronous. Place your logic inside the success.

    //Keep track of number of errors
 var errors = 0;
 //Keep track of error messages
 var errorMsg = "";

//Check if the passwords match (this part works as expected)
 if($("#password").val() != $("#repeat").val()) {
     errors++;
     errorMsg += "<li>Passwords do not match!</li>";
 }

     //Now check if the user exists
     var userName = $("#user").val();
    $.ajax({   
        type: "POST",
        data : {'user': userName},
        cache: false,  
        url: "js/ajax/addUser.php?action=checkuser",   
        success: function(data){
            var result = parseInt(data);
            //For debugging purposes
            alert("Before checking the data, # of errors is: " + errors);
            if(result > 0) {
                errors++;
                errorMsg += "<li>A user with the name <strong>" + userName + "</strong> already exists!</li>";
            }
            //For debugging purposes
            alert("After checking the data, # of errors is: " + errors);

            if(errors > 0) {
                //Output error message
            }
            else {
                //Send the form
            }
        }
    });
    //For debugging purposes
    alert("Before validating the form, # of errors is: " + errors);
    • 0