Limit image upload size

Question

I have a script for uploading images, it works fine but I would like to limit the image size to a maximum of 2 mb, I have tried a few things but without success, I am not one of the best at this so I would be very grateful for some help, follow the code

$(document).ready(function(){
   $("#but_upload_w").click(function(){
       var fd = new FormData();
        var files = $('#file_w')[0].files;
        if(files.length > 0 ){
           fd.append('file',files[0]);

           $.ajax({
              url: 'host/profile/upload.php',
              type: 'post',
              data: fd,
              contentType: false,
              processData: false,
              success: function(response){
                 if(response != 0){
                    $("#up-01").attr("value",response); 
                    $("input").show(); // Link img
                 }else{
                    alert('failed');
                 }
              },
           });
        }else{
           alert("select");
        }
    });
});

<?php

if(isset($_FILES['file']['name'])){
$filename = $_FILES['file']['name'];
$location = "upload/".$filename;
   $imageFileType = pathinfo($location,PATHINFO_EXTENSION);
   $imageFileType = strtolower($imageFileType);
   $temp = explode(".", $_FILES["file"]["name"]);
$newfilename = round(microtime(true)) . '.' . end($temp);
$valid_extensions = array("jpg","jpeg","png");
$response = 0;

   if(in_array(strtolower($imageFileType), $valid_extensions)) {

   if(move_uploaded_file($_FILES["file"]["tmp_name"], "upload/".$newfilename)){
          
    $response = "host/profile/upload/".$newfilename;
      }
   }
echo $response;
   exit;
}

echo 0; ?>

Answer 1

if(isset($_FILES['uploaded_file'])) {
    $errors     = array();
    $maxsize    = 2097152;
    $acceptable = array(
        'application/pdf',
        'image/jpeg',
        'image/jpg',
        'image/gif',
        'image/png'
    );

    if(($_FILES['uploaded_file']['size'] >= $maxsize) || ($_FILES["uploaded_file"]["size"] == 0)) {
        $errors[] = 'File too large. File must be less than 2 megabytes.';
    }

    if(!in_array($_FILES['uploaded_file']['type'], $acceptable)) {
        $errors[] = 'Invalid file type. Only PDF, JPG, GIF and PNG types are accepted.';
    }

    if(count($errors) === 0) {
        move_uploaded_file($_FILES['uploaded_file']['tmpname'], '/store/to/location.file');
    } else {
        foreach($errors as $error) {
            echo '<script>alert("'.$error.'");</script>';
        }

        die(); //Ensure no more processing is done
    }
}

Look into the docs for move_uploaded_file() for more information.