Comet doesn’t have to be a hack. Currently, as we saw last time, Comet relies on undocumented loopholes and workarounds, each one with some drawbacks. We can make Comet work effectively in every browser, using streaming transports on subdomains of the same second-level domain, or using script tag long polling across domains. But this leaves Comet developers implementing (and more frustratingly, debugging) several transports across several browsers. Traps are numerous and easy to stumble into.
event-source is the future of all Comet things.