event_extend.js

const EventEmitter = require("events");
function wrap(ev, def){
  ev.__events = ev._events;
  ev._eif = {};
  ev._dobreak = {};
  ev._events = new Proxy(ev.__events, {
    get: function(t, p, r) {
      if(p == "newListener") return;
      if( !ev.__events[p] || (typeof ev.__events[p] == "object" && ev.__events[p].length == 0)) {
        return def;
      }
      if( typeof ev.__events[p] == "function" ) {
        ev.__events[p] = [ev.__events[p]];
      }
      if(typeof ev.__events[p] == "object" && ev.__events[p].length == 2) {
        ev.__events[p] = [ev.__events[p][1]];
      }
      return new Proxy(ev.__events[p], {
        get: function(_t, _p, _r){
          if(_p == "length") return ev.__events[p].length;
          return function ef(...args){
            if( ev._eif[p] && ev._eif[p][_p] && ev._eif[p][_p](...args) ) return;
            if( ev._dobreak[p] ) return;
            let ret = ev.__events[p][_p](...args);
            ev._dobreak[p] = ret;
          };
        }
      });
    }
  });
  ev.sif = function(name, id, func){
    if( ev.__events[name] && ev.__events[name][id] ) {
      if( !ev._eif[name] ) ev._eif[name] = {};
      ev.__events[name][id] = func;
    }
  }
}
let e = new EventEmitter();
wrap(e, (...a)=>console.log(a,"?"));
e.on("test",console.log);
e.emit("test", 1);
e.sif("test", 0, n => console.log(n+"!")+1 );
e.emit("test", 3);
e.emit("test", 1);
e.emit("test1", 2);