@xlcyun/event-man

Event-Man

Event Man is a event emitter which support async/sync listener, and is flexiable to customize how to the wait async listeners to finish.

installation

npm install --save @xlcyun/event-man

Usage

const EventMan = require("./EventMan.js")

let event = new EventMan()

event.on("finished", async name => {
  console.log("Finished by " + name)
})

await event.emit("finished", "Richard").once

Output:

Finished by Richard

As we know, async is a syntactic sugar of Promise, async function will return a Promise. When you emit an event, Event Man will call all the async/sync listener, and save the returned Promises.

If you access the getters all, any, race or allFinish, rather than once which has a side effect of clearing all the returned Promises, you can retrieve the results multiple times:

let allFinish = await event.emit("finished", "Richard").allFinish
...
let all = await event.all // retrieve using all getter.

You can call clear() to clear the Promises that created and stored in Event Man of the last time emition.

await event.emit("clear")
event.clear()
// or
await event.emit("clear").clear()

Be aware that emit function return the instance of Event Man itself.

call clearAll() to clear all the Promises stored in Event Man.

event.clearAll()

once

let result = await event.emit("finished").once

Return a Promise which works like Promise.all.

It also will clear the Promises that created by the last time emition. Therefore is equal to:

let result = await event.emit("finished").all
event.clear()

result will be a array contains the values of all async listeners return.

all

Works like Promise.all.

let result = await event.emit("finished").all

any

Works like Promise.any

let result = await event.emit("finished").any

race

Works like Promise.race

let result = await event.emit("finished").race

allFinish

let result = await event.emit("finished").allFinish

The Promise returned by allFinish will never be reject, but resolve with a array contains the results returned by async function(resolved value or rejected value), check on the example:

const resolvedFunc = async function() {
  return "resolved function"
}
const rejectedFunc = async function() {
  throw new Error("rejected")
}

const EventMan = require("./EventMan.js")

async function allFinishExample() {
  let event = new EventMan()

  event.on("allFinish", resolvedFunc)
  event.on("allFinish", rejectedFunc)

  let res = await event.emit("allFinish").allFinish
  console.log(res)
}
allFinishExample()

Output:

[ 'resolved function',
  Error: rejected
      at EventMan.rejectedFunc (E:\Project\EventMan\wziuqsp3w_code_chunk:5:9)
      at EventMan.emit (E:\Project\EventMan\EventMan.js:56:48)
      at allFinishExample (E:\Project\EventMan\wziuqsp3w_code_chunk:16:25)
      at Object. (E:\Project\EventMan\wziuqsp3w_code_chunk:19:1)
      at Module._compile (internal/modules/cjs/loader.js:776:30)
      at Object.Module._extensions..js (internal/modules/cjs/loader.js:787:10)
      at Module.load (internal/modules/cjs/loader.js:653:32)
      at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
      at Function.Module._load (internal/modules/cjs/loader.js:585:3)
      at Function.Module.runMain (internal/modules/cjs/loader.js:829:12) ]