Revisions to Execute promise tree in order of declaration

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occurred Jan 9, 2019 at 13:11

added 78 characters in body

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edited Jan 7, 2019 at 19:29

153
6

let order = 0
const promiseTree = (name, children) => 
  Promise.all([
    new Promise(res => res(() => `${name} order:${order++}`)),
    children && Promise.all(children)
  ])
const recursivelyCall = x => 
  Array.isArray(x)
    ? x.map(recursivelyCall)
    : typeof(x) === 'function' ? x() : x

promiseTree('root', [
  promiseTree('child', [
    promiseTree('grandchild', [
      promiseTree('great grandchild')
    ])
  ])
])
// traverse the returned values and call the functions in declared order
.then(recursivelyCall)
.then(console.log)

<script src="https://codepen.io/synthet1c/pen/KyQQmL.js?concise=true"></script>

let order = 0
const promiseTree = (name, children) => 
  Promise.all([
    new Promise(res => res(() => `${name} order:${order++}`)),
    children && Promise.all(children)
  ])
const recursivelyCall = x => 
  Array.isArray(x)
    ? x.map(recursivelyCall)
    : typeof(x) === 'function' ? x() : x

promiseTree('root', [
  promiseTree('child', [
    promiseTree('grandchild', [
      promiseTree('great grandchild')
    ])
  ])
])
.then(recursivelyCall)
.then(console.log)

<script src="https://codepen.io/synthet1c/pen/KyQQmL.js?concise=true"></script>

let order = 0
const promiseTree = (name, children) => 
  Promise.all([
    new Promise(res => res(() => `${name} order:${order++}`)),
    children && Promise.all(children)
  ])
const recursivelyCall = x => 
  Array.isArray(x)
    ? x.map(recursivelyCall)
    : typeof(x) === 'function' ? x() : x

promiseTree('root', [
  promiseTree('child', [
    promiseTree('grandchild', [
      promiseTree('great grandchild')
    ])
  ])
])
// traverse the returned values and call the functions in declared order
.then(recursivelyCall)
.then(console.log)

<script src="https://codepen.io/synthet1c/pen/KyQQmL.js?concise=true"></script>

Added basic recursiveCall example

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edited Jan 7, 2019 at 19:08

synthet1c

153
6

If you resolve a closure, then recursively call the callbacks once all promises are complete the order can be corrected.

let order = 0
const promiseTree = (name, children) => 
  Promise.all([
    new Promise(res => res(() => `${name} order:${order++}`)),
    children && Promise.all(children)
  ])
const recursivelyCall = x => 
  Array.isArray(x)
    ? x.map(recursivelyCall)
    : typeof(x) === 'function' ? x() : x

promiseTree('root', [
  promiseTree('child', [
    promiseTree('grandchild', [
      promiseTree('great grandchild')
    ])
  ])
])
.then(recursivelyCall)
.then(console.log)

<script src="https://codepen.io/synthet1c/pen/KyQQmL.js?concise=true"></script>

If you resolve a closure, then recursively call the callbacks once all promises are complete the order can be corrected.

let order = 0
const promiseTree = (name, children) => 
  Promise.all([
    new Promise(res => res(() => `${name} order:${order++}`)),
    children && Promise.all(children)
  ])
const recursivelyCall = x => 
  Array.isArray(x)
    ? x.map(recursivelyCall)
    : typeof(x) === 'function' ? x() : x

promiseTree('root', [
  promiseTree('child', [
    promiseTree('grandchild', [
      promiseTree('great grandchild')
    ])
  ])
])
.then(recursivelyCall)
.then(console.log)

<script src="https://codepen.io/synthet1c/pen/KyQQmL.js?concise=true"></script>

Annotated the examples

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edited Jan 7, 2019 at 18:38

synthet1c

153
6

this shows the problem with the initial code. The child promises resolve before the parent promises

This shows a possible solution of delaying the action using a closure to delay performing the action from the entire tree before the entire tree has resolved. This requires recursively calling each promise, then recursively running each returned closure once the entire tree has resolved successfully.

Added basic example of promiseTree

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edited Jan 7, 2019 at 18:31

synthet1c

153
6

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added api example

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edited Jan 7, 2019 at 17:59

synthet1c

153
6

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asked Jan 7, 2019 at 10:07

synthet1c

153
6

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