too long

I'm trying to search for an id in my json file and and remove that object with php.

In detail: I post the id with jQuery post to my delete.php and in my delete.php file I search for the id and unset it. But for some reason if I unset the first object it adds a number to my json and breaks it (I can still add more objects but breaks the first one).

// delete.php file looks like this:

if(isset($_POST['deleteData'])){
    $data = $_POST['deleteData'];
    $dataJSON = json_decode(file_get_contents('datas.json'), true);  
    for($i = 0, $dataJSONLength = count($dataJSON); $i < $dataJSONLength; $i++){
      if($dataJSON[$i][data][0][id] == $data){
        unset($dataJSON[$i]);
        echo 'deleted';// needed for callback for feedback
      }
    }
    file_put_contents('datas.json', json_encode($dataJSON));
  }

// add.php is:

if(isset($_POST['addData'])){
  $dataJSON = json_decode(file_get_contents('datas.json'), true);
  $dataJSON[] = $_POST['addData'];
  file_put_contents('datas.json', json_encode($dataJSON));
}

My datas.json file is fairly nested so I'll just post where the issue is:

[{"user":[{"browser":[{" // this is what it looks like when I add

{"1":{"user":[{"browser":[{" // this is what happens when I delete the first object. Notice "1" 

If I don't delete the first object everything works fine until the first object is deleted. Any suggestions? Thanks. (if needed I can post the whole json file)

PHP is turning your array into an object probably because unset is giving you an associative array rather than in indexed array. You should call array_splice instead of unset or else call array_values after unsetting your value per the ideas found in this post.

// your for loop:
for (...) {
    unset($dataJSON[$i]);
    ...
}
// After your for loop with all necessary values removed then call array_values to normalize the array.
$dataJSON = array_values($dataJSON);