ionic-framework/demos/collection-repeat/script.js

angular.module('contactsApp', ['ionic'])
.controller('MainCtrl', function($scope, $ionicScrollDelegate, filterFilter) {
  var letters = $scope.letters = [];
  var contacts = $scope.contacts = [];
  var currentCharCode = 'A'.charCodeAt(0) - 1;

  //window.CONTACTS is imported from contacts.js
  window.CONTACTS
    .sort(function(a, b) {
      return a.last_name > b.last_name ? 1 : -1;
    })
    .forEach(function(person) {
      //Get the first letter of the last name, and if the last name changes
      //put the letter in the array
      var personCharCode = person.last_name.toUpperCase().charCodeAt(0);
      //We may jump two letters, be sure to put both in
      //(eg if we jump from Adam Bradley to Bob Doe, add both C and D)
      var difference = personCharCode - currentCharCode;
      for (var i = 1; i <= difference; i++) {
        addLetter(currentCharCode + i);
      }
      currentCharCode = personCharCode;
      contacts.push(person);
    });

  //If names ended before Z, add everything up to Z
  for (var i = currentCharCode + 1; i <= 'Z'.charCodeAt(0); i++) {
    addLetter(i);
  }

  function addLetter(code) {
    var letter = String.fromCharCode(code);
    contacts.push({
      isLetter: true,
      letter: letter
    });
    letters.push(letter);
  }

  //Letters are shorter, everything else is 52 pixels
  $scope.getItemHeight = function(item) {
    return item.isLetter ? 38 : 52;
  };

  var letterHasMatch = {};
  $scope.getContacts = function() {
    letterHasMatch = {};
    //Filter contacts by $scope.search.
    //Additionally, filter letters so that they only show if there
    //is one or more matching contact
    return contacts.filter(function(item) {
      var itemDoesMatch = !$scope.search || item.isLetter ||
        item.first_name.toLowerCase().indexOf($scope.search.toLowerCase()) > -1 ||
        item.last_name.toLowerCase().indexOf($scope.search.toLowerCase()) > -1;

      //Mark this person's last name letter as 'has a match'
      if (!item.isLetter && itemDoesMatch) {
        var letter = item.last_name.charAt(0).toUpperCase();
        letterHasMatch[letter] = true;
      }

      return itemDoesMatch;
    }).filter(function(item) {
      //Finally, re-filter all of the letters and take out ones that don't
      //have a match
      if (item.isLetter && !letterHasMatch[item.letter]) {
        return false;
      }
      return true;
    });
  };

  //We have to figure out which scrollValue to go to for the letter
  //Luckily, we already supply the height of every item to collection-repeat,
  //so we will just use that!
  $scope.goToLetter = function(letter) {
    var scrollValue = 0;
    var contacts = $scope.getContacts();
    //Find the height of every item until we hit the given letter
    for (var i = 0, ii = contacts.length; i < ii; i++) {
      if (contacts[i].isLetter && contacts[i].letter === letter) {
        break;
      }
      scrollValue += $scope.getItemHeight(contacts[i]);
    }
    $ionicScrollDelegate.scrollTo(0, scrollValue);
  };

  $scope.scrollTop = function() {
    $ionicScrollDelegate.scrollTop();
  };
  $scope.clearSearch = function() {
    $scope.search = '';
  };
});