Question

Is there any method that invokes a function but sets the context this to the “default” value that it has when I invoke the function by doing fn()?

This method should accept an array and pass the single elements as arguments to the function, much like apply() does:

emitter = new EventEmitter();
args = ['foo', 'bar'];

// This is the desired result:
emitter.emit('event', args[0], args[1], ...);

// I can do this using apply, but need to set the context right
emitter.emit.apply(emitter, 'event', args);

// How can I trim the context from this?
emitter.emit.???('event', args);

EDIT: To clarify this, I do care about the value that this will have inside the called function – it needs to be the “normal” context it has when doing emitter.emit(), not the global object or anything else. Otherwise, this will break things sometimes.

Answer 1

Just set the first parameter to the global object (i.e. window in a browser)

In ES3 browsers you could pass null instead and it would be automatically be changed to the global object, but that behaviour has been removed in the ES5 specifications.

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EDIT it sounds like you just need a new function:

EventEmitter.prototype.emitArgs = function(event, args) {
    this.emit.apply(this, [event].concat(args));
}

at which point you can just call:

emitter.emitArgs('event', args);

(EDIT thanks to @Esalija for [].concat)