Async map with limited parallelism in Node.js

Learn a simple but clever technique to use JavaScript generators for controlling parallelism when mapping a huge array using async functions. The result is a reusable pattern to process large arrays asynchronously while keeping resource consumption fixed and avoiding external penalties like API rate limits We investigate the code using snippets and diagrams as well as an example. All the code is included in the accompanying repository which is free to modify under the permissive MIT license.