Function on

samples/common/codehighlight/codemirror.js:534–543

(emitter, type, f)

  var noHandlers = [];

  var on = function(emitter, type, f) {
    if (emitter.addEventListener) {
      emitter.addEventListener(type, f, false);
    } else if (emitter.attachEvent) {
      emitter.attachEvent("on" + type, f);
    } else {
      var map = emitter._handlers || (emitter._handlers = {});
      map[type] = (map[type] || noHandlers).concat(f);
    }
  };

  function getHandlers(emitter, type) {
    return emitter._handlers && emitter._handlers[type] || noHandlers