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  1. /*
  2.  
  3. *** Publish/Subscribe global events functions - implementation of pubsub pattern for loose coupled components ***
  4.  
  5. Usage:
  6.  
  7. * Publish global application event:
  8.  
  9. publish("unique event name / category / subcategory", arg1, arg2, arg3);
  10. or
  11. publish(["event1", "event2", "event3"], arg1, arg2, arg3);
  12.  
  13.  
  14. * Subscribe to global application event:
  15. (as many subscribtions as neccessary)
  16.  
  17. subscribe("unique event name", (arg1, arg2, arg3) => { console.log("Do something useful on 'unique event name'..."); });
  18. or
  19. subscribe(["event1", "event2", "event3"], () => { console.log("Do something useful on those three events ..."); });
  20.  
  21.  
  22. * To unsubscribe from global application event:
  23. (which may be necessary on componentWillUnmount because react components can't update state when component isn't mounted)
  24.  
  25. let ref = subscribe("unique event name", (arg1, arg2, arg3) => { });
  26. unsubscribe("unique event name", ref);
  27.  
  28. unsubscribe will return true if event or events where unsubscribed
  29. */
  30. const
  31.     _entries = {};
  32.  
  33. export const
  34.     subscribe = (name, handler) => {
  35.         const
  36.             doSub = n => {
  37.                 let
  38.                     entry = _entries[n];
  39.                 if (!entry) {
  40.                     entry = _entries[n] = [];
  41.                 }
  42.                 return _entries[n].push(handler) - 1;
  43.             };
  44.         if (name instanceof Array) {
  45.             let result = [];
  46.             for(let i of name) {
  47.                 result.push({"name": i, index: doSub(i)});
  48.             }
  49.             return result;
  50.         } else {
  51.             return doSub(name);
  52.         }
  53.     };
  54.  
  55. export const
  56.     unsubscribe = (name, ref) => {
  57.         let
  58.             result = false;
  59.         if (ref instanceof Array === false) {
  60.             ref = [{"name": name, index: ref}];
  61.         }
  62.         for(let item of ref) {
  63.             let entry = _entries[item.name]
  64.             if (!entry) {
  65.                 continue;
  66.             }
  67.             let index = entry.indexOf(item.index);
  68.             if (index === -1) {
  69.                 continue;
  70.             }
  71.             entry.splice(index, 1);
  72.             if (!result) {
  73.                 result = true;
  74.             }
  75.         }
  76.         return result;
  77.     };
  78.  
  79. export const
  80.     publish = (name, ...args) => {
  81.         const
  82.             doPub = n => {
  83.                 const
  84.                     entry = _entries[n];
  85.                 if (!entry) {
  86.                     return;
  87.                 }
  88.                 entry.forEach(f => f.apply(this, args));
  89.             };
  90.         if (name instanceof Array) {
  91.             for(let i of name) {
  92.                 doPub(i);
  93.             }
  94.         } else {
  95.             doPub(name);
  96.         }
  97.     };
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