third_party/polymer/components-chromium/core-signals/core-signals-extracted.js

   1
   2 (function(){
   3
   4   Polymer('core-signals',{
   5     attached: function() {
   6       signals.push(this);
   7     },
   8     removed: function() {
   9       var i = signals.indexOf(this);
  10       if (i >= 0) {
  11         signals.splice(i, 1);
  12       }
  13     }
  14   });
  15
  16   // private shared database
  17   var signals = [];
  18
  19   // signal dispatcher
  20   function notify(name, data) {
  21     // convert generic-signal event to named-signal event
  22     var signal = new CustomEvent('core-signal-' + name, {
  23       // if signals bubble, it's easy to get confusing duplicates
  24       // (1) listen on a container on behalf of local child
  25       // (2) some deep child ignores the event and it bubbles
  26       //     up to said container
  27       // (3) local child event bubbles up to container
  28       // also, for performance, we avoid signals flying up the
  29       // tree from all over the place
  30       bubbles: false,
  31       detail: data
  32     });
  33     // dispatch named-signal to all 'signals' instances,
  34     // only interested listeners will react
  35     signals.forEach(function(s) {
  36       s.dispatchEvent(signal);
  37     });
  38   }
  39
  40   // signal listener at document
  41   document.addEventListener('core-signal', function(e) {
  42     notify(e.detail.name, e.detail.data);
  43   });
  44
  45 })();