JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
     
         <a href="setPicture.php"><img src="data/img/admin/default.png"  ></a>
		 <input type="button" name="userName" id="Uname" class="nameUser" value="Username"/>
        <form action="setPicture.php" method="post" enctype="multipart/form-data" >
          Select image to upload:
          <input type="file" name="fileToUpload" id="fileToUpload">
          <input type="submit" value="Upload Image" name="submit">
       </form>
     
		<h2 id="titlu">Chat</h2>
		
			<div id="popUp">
				<p>Set your username:</p>
				<input type="text" name="setusername" id="userSet">
				<input type="button" id="save" class="pophide" name="save" value="save"/>
			</div>
					<div id="delPop"><p>Do you want to delete this Message?</p>
						<input type="button" id="yes" value="Yes">
						<input type="button" id="no" value="No">
					</div>
			 <div id="chat">
         </div>
     

		<textarea id="message" placeholder="Message..."></textarea>
  </div>

JavaScript

$target_dir = "data/img/admin/";
$target_file = $target_dir . basename($_FILES["fileToUpload"]["name"]);
$uploadOk = 1;
$imageFileType = pathinfo($target_file,PATHINFO_EXTENSION);
// Check if image file is a actual image or fake image
if(isset($_POST["submit"])) {
    $check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
    if($check !== false) {
        echo "File is an image - " . $check["mime"] . ".";
        $uploadOk = 1;
    } else {
        echo "File is not an image.";
        $uploadOk = 0;
    }
}
// Check if file already exists
if (file_exists($target_file)) {
    echo "Sorry, file already exists.";
    $uploadOk = 0;
}
// Check file size
if ($_FILES["fileToUpload"]["size"] > 500000) {
    echo "Sorry, your file is too large.";
    $uploadOk = 0;
}
// Allow certain file formats
if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
&& $imageFileType != "gif" ) {
    echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
    $uploadOk = 0;
}
// Check if $uploadOk is set to 0 by an error
if ($uploadOk == 0) {
    echo "Sorry, your file was not uploaded.";
// if everything is ok, try to upload file
} else {
    if (move_uploaded_file($_FILES["fileToUpload"]["tmp_name"], $target_file)) {
        echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
    } else {
        echo "Sorry, there was an error uploading your file.";
    }
}
?>