alt Hacker NewsI'm not a huge fan of using CustomEvent for this.. esp. in terms of interoperability (which for these <kb challenges probably doesnt matter)
personally, i'll just roll with something like this which also is typed etc:
export function createPubSub<T extends readonly any[]>() {
const l = new Set<(...args: T) => void>()
return {
pub: (...args: T) => l.forEach((f) => f(...args)),
sub: (f: (...args: T) => void) => l.add(f) && (() => l.delete(f)),
}
}
// usage:
const greetings = createPubSub<[string]>()
const unsubscribe = greetings.sub((name) => {
console.log('hi there', name)
})
greetings.pub('Dudeman')
unsubscribe()Replies
chrismorgan • last Wednesday at 2:26 AM
Using the event dispatch mechanism is flat-out bigger, anyway. Here’s the interface of the original script (that is, global pub/sub functions taking a name), except that the receiver site no longer needs to look at the .detail property so it’s better:
let t={};
sub=(e,c)=>((e=t[e]??=new Set).add(c),()=>e.delete(c));
pub=(n,d)=>t[n]?.forEach(f=>f(d))
(The nullish coalescing assignment operator ??= has been supported across the board for 4½ years. Avoiding it will cost six more bytes.)
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nsonha • last Wednesday at 3:36 AM
if one listener throws it will break the entire channel
If listeners of this implementation aren’t unsubscribed they can’t be garbage collected, and in a real world codebase that means memory leaks are inevitable. EventDispatcher has weak refs to its listeners, so it doesn’t have this problem.