async-singleton

make async/promise function execute only one at a time.

• https://github.com/shokai/async-singleton
• https://npmjs.com/package/async-singleton

Usage

singleton

const asyncSingleton = require('async-singleton')
 
const delay = msec => new Promise(resolve => setTimeout(resolve, msec))
 
async function countUp (n = 0) {
  for (let i = 0; i < 5; i++) {
    console.log(n + i)
    await delay(100)
  }
}

const singleCountUp = asyncSingleton(countUp)
 
singleCountUp(0) // run
singleCountUp(10) // skip this
await singleCountUp(20) // skip this, but wait for "singleCountUp(0)" to finish
 
singleCountUp(30) // run this

result

0
1
2
3
4
30
31
32
33
34

trailing

When the function being executed is finished, it is executed only once at the last.

const singleCountUp = asyncSingleton(countUp, {trailing: true})
 
singleCountUp(0) // run
singleCountUp(10) // skip
singleCountUp(20) // skip
singleCountUp(30) // run, but wait for "sinleCountUp(0)" to finish

result

0
1
2
3
4
30
31
32
33
34