Checkbox always returning true in javascript/php

Question

I'm trying to get the value of the checkbox using an Ajax/Javascript response which passes the value to PHP so i can perform a query based on the value ("Checked","Not checked")

<input type="checkbox" name="status" onclick="updateStatus(<? echo $data['id']; ?>,this.checked)">

The Javascript/Ajax code for the function "updateStatus" is as followed

function updateStatus(id,value) {
if (window.XMLHttpRequest) {
    http = new XMLHttpRequest()
} else if (window.ActiveXObject) {
    http = new ActiveXObject("Microsoft.XMLHTTP")
} else {
    alert("Your browser does not support XMLHTTP!")
}
http.abort();
http.open("GET", "../functions/ajax.php?check=update_status&id=" + id + "&checked="+value, true);
http.onreadystatechange = function () {
     if (http.readyState == 4) {
        alert(http.responseText);
     }
 }
 http.send(null)

The PHP function inside functions/ajax.php

if(isset($check) and $check == 'update_status' and isset($_GET['id'])){
    $id = mysql_real_escape_string($_GET['id']);
    $checked= mysql_real_escape_string($_GET['checked']);
if($checked == true) {
    echo "Checked";
} elseif($checked == false) {
    echo "Not checked";
} else {
    echo "Invalid response";
}

when using this code it always returned "Checked" any idea why ?

You were asked about exact value of it. Try `var_dump($_GET['checked'])` to see it in response. — Viktor S., Jan 11 '13 at 17:02
Don't `mysql_real_escape_string` data until you are about to merge it into a string of SQL. For that matter, don't use it at all, it is from [an **obsolete** database API](http://stackoverflow.com/q/12859942/19068) and should use a [modern replacement](http://php.net/manual/en/mysqlinfo.api.choosing.php). — Quentin, Jan 11 '13 at 17:04

score 5 · Answer 1 · answered Jan 11 '13 at 17:02

In the JS. value will be true or false. When you stringify either of those, you will get a string ('true' or 'false').

Thus $_GET['checked'] will be either "true" or "false" both of which == true.

To fix this on the PHP side, compare to the string "true" and the string "false"; not the boolean.

score 4 · Accepted Answer · edited Jan 11 '13 at 17:27

4

You are getting $_GET['checked'] as a String. Change to something like:

if($checked == "true") {
    echo "Checked";
} elseif($checked == "false") {
    echo "Not checked";
} else {
    echo "Invalid response";
}

edited Jan 11 '13 at 17:27

blo0p3r

6,790
8
49
68

answered Jan 11 '13 at 17:04

nimlhug

121
4

score 0 · Answer 3 · edited May 23 '17 at 12:12

This might help you in your answer https://stackoverflow.com/a/4228827/90648

You can try replacing the code

"&checked="+value

with

(value ? "&checked=true" : '')

This way you will only send the value true when it is checked, and not send anything (which you can check in PHP with isset)

or you can go with

(value ? "&checked=true" : '&checked=')

which will again, not send anything, thus empty string will be interpreted as false.

Checkbox always returning true in javascript/php

3 Answers3