Posts

  • Use eslint with Typescript, today!

    A couple of months ago Typescript team revealed that they were formally adopting eslint as the linter for Typescript, and that they were actively working to improve compatibility between eslint and typescript. What you might not know is, you can use eslint with Typescript today! Read more to see how to set up eslint on your typescript project.

  • Why are Weakmaps in Javascript not Enumerable?

    Recently a colleague of mine noticed this in the MDN description of WeakMap:

    Because of references being weak, WeakMap keys are not enumerable (i.e. there is no method giving you a list of the keys). If they were, the list would depend on the state of garbage collection, introducing non-determinism. If you want to have a list of keys, you should use a Map.

    My co-worker wondered what this meant exactly? Where does the non-determinism come from? Doesn’t the state of WeakMap still depend on garbage collection even if you can’t enumerate the keys?

  • Using Swagger/OpenAPI 2.0 in Node.js

    OpenAPI is a specification that lets you write a document which describes a REST API. From this document, you can generate documentation, generate stubs to call into your API in a variety of languages, and automatically validate requests on the server, and much more. Swagger is a set of tools that work with OpenAPI. This will walk through setting up an OpenAPI document for a typical MongoDB/Express/Node.js app.

    This is the first of a three part series.

  • 'import' vs 'import *' in Babel

    If you’re using ES6 in node.js, there’s a lot of reasons to use the new “import” keyword to import modules:

    import ld from 'lodash'; // Yay!
    const ld = require('lodash'); // Boo!
    

    The old “require” way of doing things is known as “CommonJS”. The new “import” way of doing things is known as “ES6 Modules”. One of the things you’ve probably noticed, though, is you can use the “import * as” vs “import”, and sometimes it seems to makes a difference, and sometimes it doesn’t:

    import ld from 'lodash';
    import * as ld from 'lodash';
    

    So, what’s the difference between these? Which one is “right”?

  • Setting up Logstash with Docker Revisited

    This is an updated version of this post. This is a quick and easy way to get Elasticsearch, Logstash, and Kibana up and running in Docker.

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