promise-utils

Promise-utils is a dependency-free JavaScript/TypeScript library that provides Lodash-like utility functions for dealing with native ES6 promises.

Installation

$ npm install blend-promise-utils

Usage Example

const promiseUtils = require('blend-promise-utils')
const { promises: fs } = require('fs')
const request = require('request-promise-native');
const isEmpty = require('lodash.isempty');

const MS_IN_SECOND = 1000;

async function main() {
  const cachedResponse = promiseUtils.memoize(
    async (contents) => request(contents.url),
    contents => contents.url,
    15 * MS_IN_SECOND // contents could change
  );

  const fileContents = await promiseUtils.map(
    ['file1', 'file2', 'file3'],
    async fileName => {
      const rawData = await fs.readFile(fileName);
      return JSON.parse(rawData);
    },
  );

  while (true) {
    await promiseUtils.delay(150); // avoid slamming CPU

    await promiseUtils.mapSeries(
      fileContents,
      async contents => {
        const remoteData = await cachedResponse(contents);

        const { results, errors } = await promiseUtils.settleAll([
          asyncFunction1(),
          asyncFunction2(),
          asyncFunction3(),
        ]);

        if (!isEmpty(errors)) {
          throw new Error(`Unable to settle all functions: ${JSON.stringify(errors)}`);
        } else {
          return results;
        }
      }
    )
  }

  await promiseUtils.retry(flakyFunction, { maxAttempts: 3, delayMs: 150 })(flakyFunctionArgument);

  await promiseUtils.timeout(longFunction, 60 * MS_IN_SECOND)(longFunctionArgument);
}

main()

API

• Documentation
• Past versions

Test

$ npm test

Documentation

Build docs

$ make docs

Push docs to Github

$ make push-docs

License

MIT