gistfile1.js

// API

function Wemo(devices) {
  this.devices = devices;
  this.baseURL = "http://localhost:5000/api/device/";
  
  this.state = {}
  this.checked = 0;

  this.resetState();
}

Wemo.prototype = {

  checkState: function(callback) {
    for (var i = 0; i < this.devices.length; i++) {
      this.checkStateForDevice(this.devices[i], callback)
    }
  },

  checkStateForDevice: function(device, callback) {
    var self = this;
    $.ajax({
      url: self.baseURL + device,
      type: "GET",
      dataType: "json",
      success: function(data) {

        self.updateState();

        if (checked == devices.length) {
          callback(state);

          self.resetState();
        }
      },
      error: function(data) {
        errorAlert("CheckWemo error",90000);
      }
    });
  }, 

  updateState: function(data) {
    if (this.checked == 0) {
      this.on = data.state;
    } else {
      this.on = (this.on == false) ? false : data.state;
    }
    self.checked++;
  }, 

  resetState: function() {
    this.state.on = false;
    this.checked = 0;
  }

}


// Useage

var devices = [device1, device2];
var wemo = new Wemo(devices);

wemo.checkState(function(state) {
  if (state.on) {
    alert("on");
  } else {
    alert("off");
  }
});