anchor.diff:        outputElement.innerHTML = '<span style="color:red">' + error + '</span>';
       });
   
  -
  -
  -p.
  -  See also #[a(href="demos/tree.html") Tree demo] — Bacon.js vs Kefir.js performance comparison.
  +hr
  +
  +p.
  +  See also the #[a(href="demos/tree.html") "Tree" demo] — Bacon.js vs Kefir.js performance comparison.
   
   p.
     #[img(data-emoji="information_desk_person")]
  
positive.code: 
  script.
    var clicksCount = Kefir
      .fromEvent(document.querySelector('#ex-2-btn'), 'click')
      .scan(function(sum, event) {
        return sum + 1;
      }, 0);
  
    var fixedInputNumber = Kefir
      .fromEvent(document.querySelector('#ex-2-input'), 'keyup')
      .map(function(event) {
        return event.target.value;
      })
  
negative.code: 
  pre(title='example')
    :escapehtml
      var btnClicks = Kefir.fromEvents(document.querySelector('#ex-2-btn'), 'click');
  
  p.
    Also let's create a stream of a text input value changes:
  
  pre(title='example')
    :escapehtml
      var inputValue = Kefir.fromEvents(document.querySelector('#ex-2-input'), 'keyup')
        .map(function(event) {
          return event.target.value;
        });
  