var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var eventSchema = new Schema({
    title: String,
    description: String,
    startDate: Date,
    endDate: Date,
    deadline: Date,
    duration: String,
    participants: [String]
});

module.exports = mongoose.model('events', eventSchema);

var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var slotSchema = new Schema({
  startDate: { type: String, required: true },
  startTime: { type: String, required: true },
  duration:  { type: String, required: true }
});

var participantSchema = new Schema({
  name:       { type: String, required: true },
  facebookId: { type: String, required: true },
  slot:       [slotSchema]
});

var eventSchema = new Schema({
  title:        { type: String, trim: true, required: true },
  description:  { type: String, trim: true },
  startDate:    { type: String, required: true },
  endDate:      { type: String, required: true },
  deadline:     { type: String, required: true },
  duration:     { type: String, required: true },
  participants: { type: [participantSchema], required: true }
});

module.exports = mongoose.model('events', eventSchema);

Change the schema of model.
Change the schema of model.

An example is given below:

var data = {
  title:        'event 1',
  description:  'the first event',
  startDate:    '2014-01-02',
  endDate:      '2014-01-05',
  deadline:     '2014-01-01',
  duration:     '2',
  participants: [
    {
      name: 'John',
      facebookId: '234236367634',
      slot: [
        {
          startDate: '2014-01-03',
          startTime: '4',
          duration: '2'
        },
        ...
      ]
    },
    ...
  ]
};

Then post it with AJAX:

$.post('/newevent', data);
