Batching (Native) Promise calls in serial
MIT License | |
Copyright (c) 2017 Mark Tse | |
Permission is hereby granted, free of charge, to any person obtaining a copy | |
of this software and associated documentation files (the "Software"), to deal | |
in the Software without restriction, including without limitation the rights | |
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
copies of the Software, and to permit persons to whom the Software is | |
furnished to do so, subject to the following conditions: | |
The above copyright notice and this permission notice shall be included in all | |
copies or substantial portions of the Software. | |
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
SOFTWARE. |
const requestToExternalService = function(data) { | |
// Replace with real work here... | |
return new Promise(resolve => { | |
console.log(data); | |
// Delay demonstrates we are indeed batching | |
setTimeout(resolve, 500); | |
}); | |
}; | |
// Replace with real data | |
const BATCH_SIZE = 5; | |
const data = [...Array(21).keys()]; | |
let promiseChain = Promise.resolve(); | |
for(let i = 0; i < data.length; i += BATCH_SIZE) { | |
promiseChain = promiseChain | |
.then(() => Promise.all( | |
data | |
.slice(i, i + BATCH_SIZE) | |
.map(d => requestToExternalService(d)) | |
)); | |
} |
'use strict'; | |
const requestToExternalService = function(data) { | |
// Replace with real work here... | |
return new Promise(resolve => { | |
console.log(data); | |
// Delay demonstrates we are indeed batching | |
setTimeout(resolve, 500); | |
}); | |
}; | |
// Replace with real data | |
const data = [...Array(5).keys()]; | |
let promiseChain = Promise.resolve(); | |
data.forEach(d => | |
promiseChain = promiseChain.then(() => requestToExternalService(d)) | |
); | |
promiseChain.then(() => console.log('done')); |
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