Promise Chain Injection Example

Show how to inject a promise into an existing chain

by Daniel Latimer

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="messages">

</div>

JavaScript

new Promise((resolve, reject) => {
  log('promise 1 entered')
  resolve('promise 1 result')
  log('promise 1 exitted')
}).then(promise1Result => {
  log('promise 2 entered, was passed: ' + promise1Result)
  return new Promise((resolve, reject) => {
    log('promise A (injected promise) entered')
    resolve('promise A result')
    log('promise A exitted')    
  })
}).then(promiseAResult => {
  log('promise 3 entered, was passed: ' + promiseAResult)
})


function log(message) {
 $('#messages').append(`<div>${message}</div>`)
}