Comparing two identical strings in JQuery returns false

Question

I discovered an interesting problem with an echoed value from an AJAX request of JQuery, which I don't have an answere for:

My data == "LOCKED" never returns true (line 13)!

JQuery -> AJAX call on button-click:

$.ajax({
        url: "ajax/login_ajax_call.php",
        method: "POST",
        data: { user: usr, password: pwd }
    }).done(function(data){
            if(data == true || data == "true"){          // -> this works with data beeing true (bool) or "true" (string)
                $("#form_submit").submit();
            }
            else{
                console.log(jQuery.type(data));          // -> (string)
                console.log(data);                       // -> "LOCKED" 
                console.log(jQuery.type("LOCKED"));      // -> (string)
                if(data == "LOCKED"){                    // also tried "===" but it never returns true
                    [...]            
                }
                else{
                    [...]
                }
            }
    }); 
});

PHP(1) -> gets a value returned by a Class(PHP(2)):

include_once("../Classes/Login_check.php");
$lih = new Login_check();
$result = $lih -> check($_POST["user"], $_POST["password"]);
var_dump($result);                                     // -> string(6) "LOCKED"
echo $result;

PHP(2, "Login_check.php"):

[...]
// also tried: 
// $test = "LOCKED"; 
// var_dump($test);                                    // -> string(6) "LOCKED"
// return $test;
return "LOCKED";
[...]

Tell me if you need further informations! I hope anyone know what causes this problem!

score 9 · Accepted Answer · answered Jan 12 '16 at 13:09

9

Must be because of some white-spaces or new lines, it is always better to trim the data. Try this:

if (data.trim() == "LOCKED") {

You can also use:

if ($.trim(data) == "LOCKED") { // using jQuery.

answered Jan 12 '16 at 13:09

Praveen Kumar Purushothaman

164,888
24
203
252

Tried both, still returns false. – Y.Hermes Jan 12 '16 at 13:11
@Y.Hermes Can you kindly tell the value of `console.log(encodeURIComponent(data));` please? – Praveen Kumar Purushothaman Jan 12 '16 at 13:12
Dont know what this means :D %0D%0Astring(6)%20%22LOCKED%22%0ALOCKED – Y.Hermes Jan 12 '16 at 13:13
Wow... You have got something else is also returning. Man!!! You are returning as `"LOCKED"`. Yo!! You need to compare with `'"LOCKED"'`. LoL. – Praveen Kumar Purushothaman Jan 12 '16 at 13:14
@Y.Hermes Kindly show a screenshot and put it in your post. Looks like you are outputting something crazy. `:)` – Praveen Kumar Purushothaman Jan 12 '16 at 13:15
@Y.Hermes First, remove the `var_dump()`. Then put the `console.log()`. – Praveen Kumar Purushothaman Jan 12 '16 at 13:16
Well i know that var_dump() is also returning. This was just for testing reasons. But you are right that i forgot to remove it before testing your console.log. :'D Now it returns %0D%0ALOCKED – Y.Hermes Jan 12 '16 at 13:20
@Y.Hermes `%0D%0A` is a new line I guess. Although I don't understand why it follows `%0D`. Let's see. – Praveen Kumar Purushothaman Jan 12 '16 at 13:21
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/100479/discussion-between-praveen-kumar-and-y-hermes). – Praveen Kumar Purushothaman Jan 12 '16 at 13:22
@Y.Hermes `%0d` is the carriage return character, and `%0a` is the linefeed character. This is generated by Windows Servers. – Praveen Kumar Purushothaman Jan 12 '16 at 13:23
@Y.Hermes After removing the `var_dump()` and other things, I am definitely sure this should work now. Kindly check. – Praveen Kumar Purushothaman Jan 12 '16 at 13:23
Bad that im using an Ubuntu ;) Translatedwith @Rajesh 's help it means "\r\nLOCKED" – Y.Hermes Jan 12 '16 at 13:24
^^^ Rightly said... It is CR LF. `:)` I don't know why Ubuntu is generating CRLF. – Praveen Kumar Purushothaman Jan 12 '16 at 13:24
Not yet, but i'm still trying^^ Quick and dirty there would be an easy resolution by just deleting "\r\n" but thats not my intention of reworking and optimizing my page, LOL :D But why the hell is "\r\n" beeing added by Ubuntu/phpmyadmin/whatever on an echo? – Y.Hermes Jan 12 '16 at 13:29
@Y.Hermes Show us your full PHP Code? PasteBin or something will also be okay! `:)` Make sure you don't have an extra line, before or after `` – Praveen Kumar Purushothaman Jan 12 '16 at 13:30
@Y.Hermes Kindly check if you have some whitespaces before and after `` and remove them off. – Praveen Kumar Purushothaman Jan 12 '16 at 13:33
Nope. :/ Checked completly – Y.Hermes Jan 12 '16 at 13:37
@Y.Hermes Remove all the `var_dump`, debugger cr@p, and clean the PHP script. Now what does `console.log(encodeURIComponent(data))` say? And also what does `console.log(encodeURIComponent(trim(data)))` say? – Praveen Kumar Purushothaman Jan 12 '16 at 13:38
After correctiong your console.log(encodeURIComponent(trim(data))) to console.log(encodeURIComponent($.trim(data))) the result is: %0D%0ALOCKED and LOCKED – Y.Hermes Jan 12 '16 at 13:43
So: if(encodeURIComponent($.trim(data)) == "LOCKED") was the correct answere. – Y.Hermes Jan 12 '16 at 13:44
You don't need the `encodeURIComponent()` there. `:)` – Praveen Kumar Purushothaman Jan 12 '16 at 13:48
getting false even 2 strings are same in jquery typeof(item.pcp_name) "string" typeof(searchdata) "string" item.pcp_name.localeCompare(searchdata) 1 $.trim(item.pcp_name)==$.trim(searchdata) false searchdata "LEMERY, ROBERT" item.pcp_name "LEMERY, ROBERT" – Bhanu Pratap Nov 16 '18 at 11:53
@Bhanupratap Can you ask a question and add necessary details, I'll be able to help... `:)` – Praveen Kumar Purushothaman Nov 17 '18 at 13:53

score 2 · Answer 2 · edited Jun 20 '20 at 09:12

2

You can try JSON.parse. If value looks like "LOCKED" on console, it means its like ""LOCKED"".

Edit 1

As commented, you are getting "\r\nLOCKED" as stringified value, so you can use a regex to replace it. Following is the updated code.

Reference - How to remove all line breaks from a string?

Sample

var a = "LOCKED";
var strA = "\r\nLOCKED";
var regex = /\r?\n|\r/g;
var cleanStr = strA.replace(regex,'');
console.log(a);
console.log(strA);

console.log(strA == a);
console.log(cleanStr == a);

edited Jun 20 '20 at 09:12

Community

1
1

answered Jan 12 '16 at 13:17

Rajesh

24,354
5
48
79

Gets me a way nearer to the result: With a stringify it returns: "\r\nLOCKED" – Y.Hermes Jan 12 '16 at 13:23
1

Would get a second +1 from me but, you are right, it is solving the problem (but, that results out of another probleme). If I won't find the first mistake, i'll accept that answere, thanks a lot! – Y.Hermes Jan 12 '16 at 13:34
1

Ideally you should find why are you receiving such result from server and send it in proper format. – Rajesh Jan 12 '16 at 13:46

score 1 · Answer 3 · answered Jan 12 '16 at 13:12

Probably due to whitepace somewhere, such as a space before an opening php tag etc.

Far better to use a structured data format like json, and return a boolean propery to avoid these issues:

$result = $lih -> check($_POST["user"], $_POST["password"]);
$locked = ($result == 'LOCKED');
header('Content-Type: application/json');
echo json_encode(['locked'=>$locked]);

Javascript:

if(data.locked){

Comparing two identical strings in JQuery returns false

3 Answers3

Edit 1

Sample

Linked