Symbolism, Imagery, Allegory
It's probably no coincidence that Electra spends all of her time standing in a doorway. Physically she's straddling the palace and the outdoors; morally she's in a real pickle. Though she is staunchly committed to avenging her dad, Electra hasn't actually gone through with a murder yet. This means she's still on the threshold of moral decay – or of moral victory, depending on how you view the final vengeful act of the play.