Creating Single Page Web App using Backbone JS

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This was presented during the workshop on the topic. The complete code of the app that was created during the workshop is available at Github https://github.com/mathurakshay/explore-venues

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Creating Single Page Web App using Backbone JS

  1. 1. Creating Single Page Web App using Akshay Mathur
  2. 2. Akshay Mathur • Founding Team Member of – ShopSocially (Enabling “social” for retailers) – AirTight Neworks (Global leader of WIPS) • 15+ years in IT industry – Currently Principal Architect at ShopSocially – Mostly worked with Startups • From Conceptualization to Stabilization • At different functions i.e. development, testing, release • With multiple technologies @akshaymathu 2
  3. 3. What have we learnt • Creating basic web pages – HTML tags – CSS • Basic JavaScript and jQuery – – – – Reading and writing DOM Getting data using AJAX calls Responding to browser events jQuery templates • CoffeeScript • Object Oriented JavaScript – JS Classes – Extending classes using prototypes
  4. 4. BackboneJS • Provides MVC structure for JavaScript • Built on top of UnderscoreJS • Other than Model, View and Controller (Router) also provides Event and Collection objects – Using custom events help writing good code and eliminates use of global variables – Array of Models with same structure can be combined into Collection for ease of handling @akshaymathu 4
  5. 5. UnderscoreJS • Has nothing to do with MVC • Provides many useful functions on – Arrays – Objects – Array of Objects • BackboneJS directly extends a few functions for its objects (Classes) @akshaymathu 5
  6. 6. BackboneJS code class LoginModel extends Backbone.Model class LoginView extends Backbone.View initialize: => @template = $(’#login_template').template() @render() render: => $(@el).html $.tmpl(@template, @model.toJSON()) events: => 'click #login_btn' : ’login_handler’ login_handler: (ev) => window.mpq_track ’Login Click’ class LoginController extends Backbone.Router initialize: => @l_model = new LoginModel window.app_info @l_view = new LoginView model: model, el: ’#login_div’ @akshaymathu 6
  7. 7. Backbone View • A View is created by extending a Backbone’s view class • A View always have 2 properties: – el: An HTML element that is in the root of the View – model: Model that powers data to the View @akshaymathu 7
  8. 8. Creating View class LoginView extends Backbone.View initialize: => @template = $.template( $(’#login_template’)) @render() render: => $(@el).html $.tmpl(@template, @model.toJSON()) class LoginController extends Backbone.Router initialize: => @l_model = new LoginModel window.app_info @l_view = new LoginView model: @l_model, el: ’#login_div’ @akshaymathu 8
  9. 9. Rendering HTML • Typically a view has a template • In the render method, the template should be filled with data and inserted into el – The el can be attached to DOM before or after filling HTML class LoginView extends Backbone.View initialize: => @template = $.template $(’#login_template’) render: => $(@el).html $.tmpl(@template, @model.toJSON()) @akshaymathu 9
  10. 10. Browser Events • Defining events object within a view automatically connects functions to event handlers class LoginView extends Backbone.View events: 'click #login_btn' : ’login_handler’ login_handler: (ev) => window.mpq_track ’Login Click’ @akshaymathu 10
  11. 11. Design Views for • http://explore-venues.appspot.com/ @akshaymathu 11
  12. 12. Thinking of Views • Create a view for whole page – Base view that can handle anything as needed – It may be rendered by server • A view for each unit that is logically different – Event handling is needed within • Keep separate model for each view @akshaymathu 12
  13. 13. Zombie Views • When new views are created from a view class and attached to DOM in a way that it replaces HTML of an old view – The old view object and its events remain attached and create issues $(“#button”).click -> @view = new SomeView Class SomeView extends backbone.View render: => $(“container”).html template_html @akshaymathu 13
  14. 14. Handling Zombies • Don’t let zombies create • Use .destroy() on the View instance • Cleanup associated model if needed $(“#button”).click -> @view = new SomeView $(“#close_button”).click -> @view.destroy() @akshaymathu 14
  15. 15. @akshaymathu 15
  16. 16. Backbone Model • Model is defined extending the Backbone’s Model Class • The Model object can be created with the data coming from the server (database) • The data can be read later using .get() and set using .set() methods • Transient data (not intended to be synced with server) can be stored separately @akshaymathu 16
  17. 17. Creating Model app_info = {type: 4, name: ‘Internal Application’, protected: true } class LoginModel extends Backbone.Model initialize: => @is_changed = false class LoginRouter extends Backbone.Router initialize: => @l_model = new LoginModel app_info @akshaymathu 17
  18. 18. Data Manipulation • Read old_name = @model.get ‘name’ • Write new_name = old_name.toLower() @model.set ‘name’, new_name @model.is_changed = true @akshaymathu 18
  19. 19. Model Events • Model object raises events on change in data – changed – remove • These events may be captured (by view) and acted upon accordingly – A few properties are also set within the Model – Old and new values of the Model are also available @akshaymathu 19
  20. 20. Keeping UI Up-to-Date class LoginView extends Backbone.View initialize: => @model.bind(‘change’, @render) @render() render: => $(@el).html $.tmpl(@template, @model.toJSON()) class LoginRouter extends Backbone.Router initialize: => @l_model = new LoginModel app_info @l_view = new LoginView model:@l_model @akshaymathu 20
  21. 21. Syncing with Server • For having better control over data, one should collect data from the Model and make an AJAX call • One can also attach a URL to the Model and RESTful AJAX calls are automatically done @akshaymathu 21
  22. 22. Collections • Simple data structure for storing many instances of same model – Array of Model objects • Provides methods and properties for managing the list • Can be created by extending Collection class of Backbone @akshaymathu 22
  23. 23. Creating Collection class VenueModel extends Backbone.Model class VenueCollection extends Backbone.Collection model: VenueModel class VenueListModel extends Backbone.Model initialize: => @e_list = new VenueCollection class VenueListView extends Backbone.View initialize: => @model.e_list.bind('add', @add_venue) add_venue: (venue_model) => @akshaymathu 23
  24. 24. @akshaymathu 24
  25. 25. Backbone Router • It routes URLs to respective methods • A Router is created by extending a Backbone’s router class • Route configuration can be passed while creating the router object instance @akshaymathu 25
  26. 26. Creating Router class LoginController extends Backbone.Router initialize: => @l_model = new LoginModel window.app_info @l_view = new LoginView model: model, el: ’#login_div’ routes: “help”: “help” $(document).ready -> l_router = new LoginController() @akshaymathu 26
  27. 27. Route Configuration • Rout configuration is a JavaScript object mapping URLs to functions – URL patterns may be used as key – Data can be read from URLs and passed to functions as parameters @akshaymathu 27
  28. 28. Routes at Work routes: "help": "help” // #help "search/:query": "search", // #search/kiwis "search/:query/p:page": "search" // #search/kiwis/p7 help: -> search: (query, page)-> @akshaymathu 28
  29. 29. Catch All • Router is sometimes used for putting methods not belonging to any other Model or View • Router also acts as a glue for all other objects – Typically all basic views are initialized in router so any cross-view functionality can be implemented in router @akshaymathu 29
  30. 30. @akshaymathu 30
  31. 31. Events • Events facilitate communication amongst different objects – Data can be passed along with events • Browser raises events on user actions • Publish-Subscribe architecture avoids tight coupling between objects @akshaymathu 31
  32. 32. Backbone Events • Backbone objects also raise events on various actions – add: when a model is added to a collection. – remove: when a model is removed from a collection. – reset: when the collection's entire contents have been replaced. – change: when a model's attributes have changed. – change: when a specific attribute has been updated. – destroy: when a model is destroyed. @akshaymathu 32
  33. 33. Custom Events • Backbone’s event module can be mixed with an object – The the objects gets the ability to raise events programmatically – The object also gets the ability to listen to the events @akshaymathu 33
  34. 34. Defining Custom Events EventDispatcher = SHOW_VENUE: 'show_venue' CLEAN: 'clean' _.extend(EventDispatcher, Backbone.Events) @akshaymathu 34
  35. 35. Using Custom Events ED = EventDispatcher class VenuetView extends Backbone.View initialize: => ED.bind ED.CLEAN, @remove_self class VenueListView extends Backbone.View initialize: => @model.e_list.bind('add', @add_venue) ED.bind ED.CLEAN, @reset_col clean_old_list: => @venue_list_model.e_list.reset() ED.trigger ED.CLEAN @akshaymathu 35
  36. 36. @akshaymathu 36
  37. 37. Go Hands-on Explore FourSquare Venues http://explore-venues.appspot.com/
  38. 38. @akshaymathu 38
  39. 39. Design Views • Page view – Accordion – Google Map • Venue list view – All venue tiles • Venue view – Single venue tile • Venue details view (do later) – Popup with details of the venue @akshaymathu 39
  40. 40. Design Models • As a thumb rule, a model can be kept for each view – Page model – Venue list model – Venue model – Venue details model (do later) @akshaymathu 40
  41. 41. Create Base HTML • Head – Include Bootstrap CSS – Include JS • Google Map API, jQuery’s , jQuery template • Bootstrap, Underscore, Backbone, App’s custom • Top bar – Use navbar’s HTML from Bootstrap • Accordion – Use Bootstrap jQuery plugin’s HTML – Create accordion headers – Keep accordion bodies blank @akshaymathu 41
  42. 42. Create jQuery Templates • No template for Google Map – Map UI is completely rendered by Google APIs • Venue template – Each venue tile • Venue details template (do later) – Venue details popup – Use Bootstrap modal jQuery plugin’s HTML @akshaymathu 42
  43. 43. @akshaymathu 43
  44. 44. Create CoffeeScript
  45. 45. Basic Skeleton class VenueModel extends Backbone.Model class VenueCollection extends Backbone.Collection model: VenueModel class VenueListModel extends Backbone.Model initialize: => @e_list = new VenueCollection class VenueListView extends Backbone.View initialize: => @model.e_list.bind('add', @add_venue) class VenueView extends Backbone.View class PageModel extends Backbone.Model class PageView extends Backbone.View class VenueController extends Backbone.Router @akshaymathu 45
  46. 46. Start Execution • On DOM ready event, instantiate the router $(document).ready -> venue_controller = new VenueController • Create an instance of page model and view in initialize routine of router class VenueController extends Backbone.Router initialize: => @page_model = new PageModel @page_view = new PageView ( el: $("#maindiv"), model: @page_model) @akshaymathu 46
  47. 47. Initialize Page View • Page view initializes automatically when its instance gets created in router • Initialize venue list class PageView extends Backbone.View initialize: => @venue_list_model = new VenueListModel @venue_list_view = new VenueListView( el: $("#venue_list"), model: @venue_list_model ) @akshaymathu 47
  48. 48. Google Map • In page view, create Google Map object and render it in the div created for that • Register event handler for Google Map click event @map = new google.maps.Map( $(’#map-canvas’)[0]), map_options) google.maps.event.addListener @map, 'click', (ev) => @get_venues( ev.latLng.lat(), ev.latLng.lng()) @akshaymathu 48
  49. 49. Get Venues • Make a JSONP AJAX call to FourSquare for getting venues near the clicked location • Create a model from each venue in result and add to collection venue_model = new VenueModel item.venue @venue_list_model.e_list.add venue_model @akshaymathu 49
  50. 50. Render Venue Tile • As venue model adds into collection, the add event handler on collection is fired in venue list view @model.e_list.bind('add', @add_venue) • Handlers gets the venue view rendered and attaches it to the DOM add_venue: (venue_model) => venue_view = new VenueView( model: venue_model) tile_html = venue_view.render() $("#venue_col).append tile_html @akshaymathu 50
  51. 51. Click on Venue Tile • Venue view registers click handler by defining event map class VenueView extends Backbone.View events: "click" : 'show_details’ • Venue detail popup is to be shown outside base element (el) of the venue view so it raises an event show_details: => ED.trigger ED.SHOW_VENUE, @model @akshaymathu 51
  52. 52. Showing Details Popup • Page view listens to the event and renders details popup class PageView extends Backbone.View initialize: => ED.bind ED.SHOW_VENUE, @show_popup show_popup: (venue_model) => @detail_view = new VenueDetailView model: venue_model $(@el).append @detail_view.render() @akshaymathu 52
  53. 53. @akshaymathu 53
  54. 54. Optimization • Venue model and Venue detail model represent exactly same entity – There is always 1-1 relation • Same model may be used for both – First render should not be slow for bringing details @akshaymathu 54
  55. 55. Thanks @akshaymathu @akshaymathu 55

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