JSFiddle - React, Tailwind, and code Playground

HTML

<form class="form-horizontal" role="form" id="form_newCours">
        <div class="form-group">
            <label class="control-label col-sm-2" for="discippline">Matiere:</label>
            <div class="col-sm-4">
                <input type="text" class="form-control" id="discipline" placeholder="Matiere">
            </div>
        </div>
        <div class="form-group" align="left">
            <label class="control-label col-sm-2" for="datetimepicker">Date:</label>
            <div class="input-group col-sm-4">
                        <input type="text" class="form-control" id="datetimepicker"/>
                        <span class="input-group-addon">
                            <span class="glyphicon glyphicon-calendar"></span>
                        </span>
            </div>
        </div>
        <div class="form-group">
            <div class="col-sm-offset-2 col-sm-10">
              <div class="checkbox">
                <label><input type="checkbox" id="creneau_regulier"> Ce creneau regulier</label>
              </div>
            </div>
        </div>
        <div class="form-group">
            <div class="col-sm-offset-2 col-sm-10">
              <button type="submit" class="btn btn-default" id="btn-newCours">Ajouter</button>
            </div>
        </div>
 </form>

JavaScript

$.fn.serializeObject = function() {
  var o = {};
  var a = this.serializeArray();
  $.each(a, function() {
    if (o[this.name] !== undefined) {
      if (!o[this.name].push) {
        o[this.name] = [o[this.name]];
      }
      o[this.name].push(this.value || '');
    } else {
      o[this.name] = this.value || '';
    }
  });
  return o;
};

$(document).ready(function() {

  $('#btn-newCours').on('click', function(e) {
    e.preventDefault();
    console.log("Ici");
    // YK: Bellow is my code
    var jsonString = JSON.stringify($('#form_newCours').serializeObject());
    console.log($('#form_newCours').serialize());
    $.ajax({
      type: "POST",
      data: jsonString,
      url: "/cours/",
      contentType: "application/json"
    });
  });

});