requirebin sketch

index.js

// !! Open devtools console and click 'run' button.
//
// line 24 is responsible for reemiting received events to 'piped' emitters
// but it fails when em1 --pipes--> em2 and em2 --pipes--> em1
// when line 42 is uncommented

var events = require('events');
var wrap  = function ( emitter )
{
  emitter.pipe = function ( targetEmitter )
  {
    if (!this.pipes) this.pipes = [];
    this.pipes.push(targetEmitter);
    
    this._emit = this.emit;
    this.emit  = function ()
    {
        // emit event 'locally'
        this._emit.apply(this, arguments);
        
        // emit event in all piped emitters
        for (var i = 0; i < this.pipes.length; ++i)
        {
          this.pipes[i].emit.apply(this.pipes[i], arguments);
        }
    };
    
    return this;
  };
  
  return emitter;
};

// wrap some dummy emitters so we can connect them using firstEmitter.pipe(secondEmitter)
var em1 = wrap(new events.EventEmitter());
var em2 = wrap(new events.EventEmitter());

// pass all emitted events in em1 to em2
em1.pipe(em2);

// pass all emitted events in em2 to em1
// em2.pipe(em1); // uncomment that line and it will loop forever

em1.on('foo', function(msg) { console.log('em1::foo >', msg); });
em2.on('foo', function(msg) { console.log('em2::foo >', msg); });

// em1::foo will be handled by em1.on('foo') and em2.on('foo');
em1.emit('foo', 'emitted on em1');

// em2::foo will be handled by em2.on('foo');
// - it's also handled by em1.on('foo') when piping em2 back to em1
// but it's useless when emitters are falling into inf loop
em2.emit('foo', 'emitted on em2');

minified.js

require=function e(t,s,n){function r(o,h){if(!s[o]){if(!t[o]){var u="function"==typeof require&&require;if(!h&&u)return u(o,!0);if(i)return i(o,!0);throw Error("Cannot find module '"+o+"'")}var v=s[o]={exports:{}};t[o][0].call(v.exports,function(e){var s=t[o][1][e];return r(s?s:e)},v,v.exports,e,t,s,n)}return s[o].exports}for(var i="function"==typeof require&&require,o=0;n.length>o;o++)r(n[o]);return r}({Sk64m6:[function(e,t){function s(){this._events=this._events||{},this._maxListeners=this._maxListeners||void 0}function n(e){return"function"==typeof e}function r(e){return"number"==typeof e}function i(e){return"object"==typeof e&&null!==e}function o(e){return void 0===e}t.exports=s,s.EventEmitter=s,s.prototype._events=void 0,s.prototype._maxListeners=void 0,s.defaultMaxListeners=10,s.prototype.setMaxListeners=function(e){if(!r(e)||0>e||isNaN(e))throw TypeError("n must be a positive number");return this._maxListeners=e,this},s.prototype.emit=function(e){var t,s,r,h,u,v;if(this._events||(this._events={}),"error"===e&&(!this._events.error||i(this._events.error)&&!this._events.error.length))throw t=arguments[1],t instanceof Error?t:TypeError('Uncaught, unspecified "error" event.');if(s=this._events[e],o(s))return!1;if(n(s))switch(arguments.length){case 1:s.call(this);break;case 2:s.call(this,arguments[1]);break;case 3:s.call(this,arguments[1],arguments[2]);break;default:for(r=arguments.length,h=Array(r-1),u=1;r>u;u++)h[u-1]=arguments[u];s.apply(this,h)}else if(i(s)){for(r=arguments.length,h=Array(r-1),u=1;r>u;u++)h[u-1]=arguments[u];for(v=s.slice(),r=v.length,u=0;r>u;u++)v[u].apply(this,h)}return!0},s.prototype.addListener=function(e,t){var r;if(!n(t))throw TypeError("listener must be a function");if(this._events||(this._events={}),this._events.newListener&&this.emit("newListener",e,n(t.listener)?t.listener:t),this._events[e]?i(this._events[e])?this._events[e].push(t):this._events[e]=[this._events[e],t]:this._events[e]=t,i(this._events[e])&&!this._events[e].warned){var r;r=o(this._maxListeners)?s.defaultMaxListeners:this._maxListeners,r&&r>0&&this._events[e].length>r&&(this._events[e].warned=!0,console.error("(node) warning: possible EventEmitter memory leak detected. %d listeners added. Use emitter.setMaxListeners() to increase limit.",this._events[e].length),console.trace())}return this},s.prototype.on=s.prototype.addListener,s.prototype.once=function(e,t){function s(){this.removeListener(e,s),r||(r=!0,t.apply(this,arguments))}if(!n(t))throw TypeError("listener must be a function");var r=!1;return s.listener=t,this.on(e,s),this},s.prototype.removeListener=function(e,t){var s,r,o,h;if(!n(t))throw TypeError("listener must be a function");if(!this._events||!this._events[e])return this;if(s=this._events[e],o=s.length,r=-1,s===t||n(s.listener)&&s.listener===t)delete this._events[e],this._events.removeListener&&this.emit("removeListener",e,t);else if(i(s)){for(h=o;h-->0;)if(s[h]===t||s[h].listener&&s[h].listener===t){r=h;break}if(0>r)return this;1===s.length?(s.length=0,delete this._events[e]):s.splice(r,1),this._events.removeListener&&this.emit("removeListener",e,t)}return this},s.prototype.removeAllListeners=function(e){var t,s;if(!this._events)return this;if(!this._events.removeListener)return 0===arguments.length?this._events={}:this._events[e]&&delete this._events[e],this;if(0===arguments.length){for(t in this._events)"removeListener"!==t&&this.removeAllListeners(t);return this.removeAllListeners("removeListener"),this._events={},this}if(s=this._events[e],n(s))this.removeListener(e,s);else for(;s.length;)this.removeListener(e,s[s.length-1]);return delete this._events[e],this},s.prototype.listeners=function(e){var t;return t=this._events&&this._events[e]?n(this._events[e])?[this._events[e]]:this._events[e].slice():[]},s.listenerCount=function(e,t){var s;return s=e._events&&e._events[t]?n(e._events[t])?1:e._events[t].length:0}},{}],events:[function(e,t){t.exports=e("Sk64m6")},{}]},{},[]);var events=require("events"),wrap=function(e){return e.pipe=function(e){return this.pipes||(this.pipes=[]),this.pipes.push(e),this._emit=this.emit,this.emit=function(){this._emit.apply(this,arguments);for(var e=0;this.pipes.length>e;++e)this.pipes[e].emit.apply(this.pipes[e],arguments)},this},e},em1=wrap(new events.EventEmitter),em2=wrap(new events.EventEmitter);em1.pipe(em2),em1.on("foo",function(e){console.log("em1::foo >",e)}),em2.on("foo",function(e){console.log("em2::foo >",e)}),em1.emit("foo","emitted on em1"),em2.emit("foo","emitted on em2");

package.json

{
  "name": "requirebin-sketch",
  "version": "1.0.0",
  "dependencies": {}
}

page-head.html

<style type='text/css'>html, body { margin: 0; padding: 0; border: 0; }
body, html { height: 100%; width: 100%; }</style>

requirebin.md

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