How to convert Ajax response to string to compare with JS string

Question

How do I convert Ajax response into plain text string?I have global variable and I store the ajax response to it but when I'm going to compare it with javascript string when even they are equal It returns false.

Here is my code:

function checkUsn(){
    var usn = document.getElementById("usn").value;
    if(usn){
        $.ajax({
            type: 'post',
            url: 'checkdata.php',
            data: {
                emp_username: usn,
            },
            success: function(response){
                console.log(response);
                myGlobalContainer.usn = response; //convert it to compare with string
                $('#status').html(response);
            }
        });
    }
}

in console when I type the existing username in database it logs OK. This OK stores in myGlobalContainer.usn, but when I do comparison like code below it return false.

if(myGlobalContainer.usn == "OK"){
return true;
}else{
return false;
}

I will add php file.

<?php
header("Content-Type: text/plain");
include 'db_config.php';
$conn = new mysqli($db_servername, $db_username, $db_password, $db_name);

if(isset($_POST['emp_username'])){
    $usn = $_POST['emp_username'];

    $checkdata = "SELECT emp_username FROM emp_details where emp_username='$usn'";

    $query = mysqli_query($conn, $checkdata);

    if(mysqli_num_rows($query) > 0){
        echo "OK";
    }else{
        echo "Your Username not exist";
    }
    exit();
}

if(isset($_POST['emp_pw']) && isset($_POST['emp_usn'])){
    $pw = $_POST['emp_pw'];
    $usn = $_POST['emp_usn'];

    $get_pw = "SELECT emp_password FROM emp_details where emp_username='$usn'";

    $query = mysqli_query($conn, $get_pw);

    //$get_num_rows = mysqli_num_rows($query);
    //echo $get_num_rows;

    $row = mysqli_fetch_assoc($query);
    //echo $row["emp_password"];

    // check if password is match with username
    if($pw == $row["emp_password"]){
        echo "MATCH";
    }else{
        echo "Wrong password";
    }
    exit();
}
?>

Please help Thanks!

I don't think the problem is the string comparison, response is already a string in all likeliness, the problem is probably that you are executing the code where you compare myGlobalContainer.usn == "OK" before the value is set in the Ajax callback. The callback is executed asynchronously. — Patrick Hund
– Patrick Hund, Commented Aug 11, 2018 at 9:22
When / where exactly is your if(myGlobalContainer.usn == "OK") code executing? — Phil
– Phil, Commented Aug 13, 2018 at 1:17

Basch · Accepted Answer · 2018-08-13 01:29:34Z

2

I've change my code to

    success: function(response){
        console.log(response);
        myGlobalContainer.usn = response.trim(); //convert it to compare with string
        $('#status').html(response);

and It works but Guys thanks for your help very appreciated! also thanks to this question Ajax response doesn't equal what I think it should

answered Aug 13, 2018 at 1:29

Basch

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2 Comments

Phil Over a year ago

You must have had some whitespace (newline, etc) in your PHP that is not shown in your question.

Razvan_TK9692 Over a year ago

Phil> nope - I had the same issue, and my PHP was clean - but it does need a trim in JavaScript for some reason it seems

Quentin · Accepted Answer · 2018-08-11 10:08:44Z

1

By default, jQuery's ajax function will determine the type of data it is receiving from the Content-Type response header.

You can override that with the dataType parameter.

$.ajax({
    dataType: "text",
    // etc etc
});

… however, since the response seems to be "OK" and not HTML, it is likely that your PHP should be adjusted so it outputs the correct Content-Type:

<?php
    header("Content-Type: text/plain"); # Override the default (text/html)
    echo "OK";

So also make sure that the response is really simply "OK" and that you are not outputting (for example) "OK" followed by a new line.

answered Aug 11, 2018 at 10:08

Quentin

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1 Comment

Basch Over a year ago

Hi sir Quentin It doesn't work Even I put header("Content-Type: text/plain"); in php file and add dataType: "text", on ajax.

bUff23 · Accepted Answer · 2018-08-11 10:06:04Z

0

i seem you should use a function in ajax success.

var myGlobalContainer.usn = "";
function signAndCompare(str)
{
     myGlobalContainer.usn = str
     if(myGlobalContainer.usn == "OK")
         {
             console.log("true");
             return true;
          }
     console.log("false");
     return false;
 }

function checkUsn(){
var usn = document.getElementById("usn").value;
if(usn){
    $.ajax({
        type: 'post',
        url: 'checkdata.php',
        data: {
            emp_username: usn,
        },
        success: function(response){
            console.log(response);
            signAndCompare(response);//this line: **compare** and sign response
            $('#status').html(response);
        }
    });
}

edited Aug 11, 2018 at 10:06

bUff23

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answered Aug 11, 2018 at 9:34

Alireza Hejazi

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2 Comments

Basch Over a year ago

Hi sir Alireza thank you for your response. I've tried the your solution but It doesn't work

Phil Over a year ago

FYI, var myGlobalContainer.usn = ""; is invalid. You want var myGlobalContainer = { usn: '' } or something like that

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