js-promise-queue

Runs JavaScript Promises in a queue

Installation

npm install js-promise-queue --save

Usage

The module exports a function that takes 3 arguments:

1. items: An array of items that will generate Promises
2. factory: A factory function that:
   • Is called for each item, with its value as the first parameter and its index as the second
   • Returns a Promise
3. options: An optional options object, with one or more of these properties:
   • interval: Time (in milliseconds) to wait in between Promise executions

Examples

• Run Promises sequentially, printing the result at the end

  const promiseQueue = require('js-promise-queue')
  
  const factoryFn = value => {
    return new Promise((resolve, reject) => {
      setTimeout(() => resolve(value), 2000)
    })
  }
  
  promiseQueue([1, 2, 3], factoryFn).then(console.log)
  // Returns: [1, 2, 3]

• Run Promises sequentially with an interval of 3 seconds between each

  const promiseQueue = require('js-promise-queue')
  
  const factoryFn = (value, index) => {
    console.log('Promise: starting...')
  
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        console.log('Promise: done after 2 seconds')
  
        resolve(value)
      }, 2000)
    })
  }
  
  promiseQueue([1, 2, 3], factoryFn, {
    interval: 3000
  }).then(console.log)
  // Returns: [1, 2, 3]
  
  /*
    00:00:00: Prints "Promise: starting..."
    00:00:02: Prints "Promise: done..."
    00:00:05: Prints "Promise: starting..."
    00:00:07: Prints "Promise: done..."
    00:00:10: Prints "Promise: starting..."
    00:00:12: Prints "Promise: done..."
  */