Observables

script.js

// Code goes here
window.onload = function() {
  var Observable = Rx.Observable;
  var textbox = document.getElementById('textbox');
  var keypresses = Observable.fromEvent(textbox, 'keypress');
  var results = document.getElementById('results');
  var searchButton = document.getElementById('searchButton');
  var searchButtonClicks = Observable.fromEvent(searchButton, 'click');
  
  function getWikipediaSearchResults(term) {
    return Observable.create(function forEach(observer) {
        var cancelled = false;
        var url = 'http://en.wikipedia.org/w/api.php?action=opensearch&format=json&search='
        + encodeURIComponent(term) + '&callback=?';
        $.getJSON(url, function(data) {
          if (!cancelled) {
            observer.onNext(data[1]);
            observer.onCompleted();
          }
        });
        
        return function dispose() {
          cancelled = true;
        };
      });
  }
 
  searchButtonClicks.forEach(function() {
    document.getElementById('searchForm').style.display = "block";
  });
  
  //[1,2,3].map(x => [x]) -> [[1],[2],[3]]
  
  var searchResultSets = 
    searchButtonClicks.
      map(function() {
        var closeClicks = Observable.fromEvent(document.getElementById('closeButton'), 'click');
        return keypresses.
          // {.'a'..'b'.......'c'..'d'.....
          throttle(20).
          // {...........'b'............'d'.....
          map(function(key) {
            return textbox.value;
          }).
          // {...........'ab'.....'ab'....'abc'..
          distinctUntilChanged().
          // {...........'ab'.............'abc'
          map(function(search){
             return getWikipediaSearchResults(search).retry(3);
          }).
          switchLatest().
          takeUntil(closeClicks)
          // {........................................["abacus"]...
      }).
      switchLatest();
      
  searchResultSets.forEach(
    function(resultSet) {
      results.value = JSON.stringify(resultSet);
    },
    function(error) {
      alert('Not working. Try again later.')
    });
}