`waitForInitialization()` should resolve with the client

[rmanalan]

It's best to resolve promises with the object that the user expects. This way in an async/await world, the value resolved can be assigned to a var:

const ldclient = await ldClient.waitForInitialization();
console.log(await ldclient.allFlags(<user>));

In the current version, the above code would yield a null or undefined value for ldclient.

[apucacao]

Hi Rich,

I'm curious: since you already have ldClient, do you need to re-assign it (to ldclient)?

[rmanalan]

@apucacao we're using electrolyte for dependency injection and when I bring in the ldclient, it comes in as a promise... like so:

'use strict';

const ldClient = require('ldclient-node');

module.exports = function (ldSettings, logger) {
  const ldclient = ldClient.init(ldSettings.key, { logger });
  // I would use `waitForIntialization()` here since it returns a promise.
  // However, the current version doesn't resolve a value.
  // https://github.com/launchdarkly/node-client/pull/106
  return new Promise(function (resolve, reject) {
    ldclient.once('ready', function () {
      resolve(ldclient);
    });
    ldclient.once('failed', function (err) {
      reject(err);
    });
  });
};

module.exports['@require'] = ['settings/launchdarkly', 'logger/launchdarkly'];
module.exports['@singleton'] = true;

This can then be injected into other modules like so:

const ldclient = await trello.create('launchDarkly'); // returns ldclient

As you can see in the above code, if I'd used waitForIntialization(), the return value from the trello.create() would have been null.

[eli-darkly]

In general I'm somewhat reluctant to make API design decisions based on what would produce the shortest possible code in one particular framework, but making this change can't hurt.

[rmanalan]

@eli-darkly fwiw, waitForInitialization() isn't documented yet. Also, it's generally good practice to resolve a promise with a value.

[eli-darkly]

It was added to the doc page earlier today, and was already present in index.d.ts (where it is documented as returning a Promise\<Void>). I will update that page once the next release goes out.

[eli-darkly]

BTW, I only realized this after adding a unit test, but this PR was slightly incomplete - it would not resolve with a value unless initComplete was already true. But this has been fixed in the release version of the code.

[eli-darkly]

Released in v5.2.0.