JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script src="https://rawgit.com/mervick/emojionearea/master/dist/emojionearea.js"></script>
<link rel="stylesheet" href="https://rawgit.com/mervick/emojionearea/master/dist/emojionearea.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<form class="input-group" id="form" >
  <input class="form-control" type="text" maxlength="10" id="mensagem" name="mensagem" placeholder="Digite...">
  <input id="id_user" name="id_user" type="hidden" value="<?php echo $id; ?>">
  <div class="input-group-btn">
     <button class="btn btn-success" id="BotaoId" onclick="AlteraConteudo()"><i class="fa fa-plus"></i></button>    
  </div>
</form>

CSS

* {
  font-family: Arial, Helvetica, san-serif;
}
.emojionearea {
  width: 90%;
}
.emojionearea .emojionearea-editor {
    min-height: 1em;
}
.btn btn-success {
    width: 1%;
    display: block;
}

JavaScript

window.AlteraConteudo = function() {
  var text = $('#mensagem').data("emojioneArea").getText();
  console.log('AlteraConteudo.text = ', text);
  
 // Variável com os dados que serão enviados ao PHP
 var dados = "mensagem=" + text;
 ajax.open("GET", "retorna_informacoes.php?" + dados, false);
 ajax.setRequestHeader("Content-Type", "text/html");
 ajax.send();
 
  $('#mensagem').data("emojioneArea").setText('');
}

$(document).ready(function() {
	$("#mensagem").emojioneArea({
    inline: false,
    events: {
      keypress: function (editor, event) {
        if (event.which == 13) {
          event.preventDefault();
          // I need to run the function 
					AlteraConteudo();
        }
      }
    }
  });
});