Kevin He kevinxh

Boolean() or !! (double bang, double negation)?

What's the best way to answer the question "true or false?" in JavaScript

JavaScript does not bother you too much with types (at first), which is both a blessing and a cure. But we all know the Boolean type. Boolean variables can either be true or false. Yes or no.

Every value in JavaScript can be translated into a boolean, true or false. Values that translate to true are truthy, values that translate to false are falsy. Simple.

This is about two ways to make that translation.

Python relative imports in AWS Lambda fail with attempted relative import with no known parent package

The Problem

In AWS Lambda if I attempt an explicit relative import like this

.
├── lambda_file.py
└── example.py

This will guide you through setting up a replica set in a docker environment using.

Docker Compose
MongoDB Replica Sets
Mongoose
Mongoose Transactions

Thanks to https://gist.github.com/asoorm for helping with their docker-compose file!

I've been deceiving you all. I had you believe that Svelte was a UI framework — unlike React and Vue etc, because it shifts work out of the client and into the compiler, but a framework nonetheless.

But that's not exactly accurate. In my defense, I didn't realise it myself until very recently. But with Svelte 3 around the corner, it's time to come clean about what Svelte really is.

Svelte is a language.

Specifically, Svelte is an attempt to answer a question that many people have asked, and a few have answered: what would it look like if we had a language for describing reactive user interfaces?

A few projects that have answered this question:

Debugging Node.js web applications running on Heroku using ngrok

Introduction

Heroku only allows each dyno to send and receive external network traffic on a single port, which means you can't simply run node --debug server.js and attach your debugger to your-app.herokuapp.com:5858.

To work around this, you can use ngrok and Heroku ngrok Buildpack to tunnel to the debugger's port and access it externally.

We are planning on building a Node.js service. Here's our evaluation of the current ORM landscape:

Last updated: May 2 2016

Objection.js
- http://vincit.github.io/objection.js/#introduction
- Bad: API is Promise based and bulky. This means people can forget to have an error handler due to not being error first
  - http://vincit.github.io/objection.js/#getting-started
- Good: Uses JSON schema for validation; this means content should be relatively reusable between server/browser
http://vincit.github.io/objection.js/#validation

npm rank

This gist is updated daily via cron job and lists stats for npm packages:

Top 1,000 most depended-upon packages
Top 1,000 packages with largest number of dependencies
Top 1,000 packages with highest PageRank score

	const useThunk = (reducer, initState) => {
	const [state, dispatch] = useReducer(reducer, initState);
	const thunkDispatch = action => {
	if (typeof action === "function") {
	action(dispatch, () => state);
	} else {
	dispatch(action);
	}
	};
	return [state, thunkDispatch];

	About this gist

	With this gist I wanted to freeze some concepts about BackboneJS that could
	save some time in the future either to me if I needed to use this functionality
	again, or to somebody else.

	This implementation addresses the need to retrieve some data from an API and
	to populate a BackboneJS collection accordingly, storing the retrieved items
	as Models inside the Collection.
	If you want to see this functionality built into an application, have a look

	import { h, Component } from 'preact';


	/** Creates a new store, which is a tiny evented state container.
	* @example
	* let store = createStore();
	* store.subscribe( state => console.log(state) );
	* store.setState({ a: 'b' }); // logs { a: 'b' }
	* store.setState({ c: 'd' }); // logs { c: 'd' }
	*/