Thomas Junghans tjunghans

Frontend Developer Guidelines

Pull Requests and Code Reviews

Creating Pull Requests

One commit per pull request. Squash commits before merging.
Strive for one feature or bugfix per pull request.
Link the pull request to a jira using the git branch name.
The branch name of the pull request has the following convention: feature|bugfix/MTB-####-short-description-of-change

Increase ulimit on a systemd service

Locate the service under /etc/systemd/system and edit it with vim. Add the following to the [Service] section of the file:

LimitNOFILE=65536

This is the equivalent of ulimit -n.

Octave

This is a summary of the Octave Tutorial of the Coursera Machine Learning course by Andrew Ng.

Basic Operations

>> 5 + 6
ans = 11

Recursive Promises

You have a function authenticate which returns a resolved promise on success or reject on failure. If the authentication failed the process should be repeated. This can be a achieved with a recursive promise.

Example

let counter = 0;

Promises in Sequence

If you have multiple promises, an array of promises, and you want to perform an action after they all have resolved you can use Promise.resolve(). However if you'd like the same result, whilst having the promises called in order you will need to come up with a custom solution because there is no api for that.

Let's create a promise factory to generate our promises that we want to execute in sequence:

function createP(id) {

Checking the Type of an API Response in TypeScript

TODO: Look at Typescript User defined Type Guards

Although the title contains "TypeScript" what I'm about to show is not TypeScript specific and can and should also be done with JavaScript. The reason I am writing in the context of TypeScript is because we rely on TypeScript for type checking in most cases. An exception is when we get data from an API response such as HTTP GET and expect the data to be a certain type.

The advantage of TypeScript is that it can check variable, property, argument and function/method return types during compilation, catching errors that would possibly be thrown during run time. TypeScript cannot anticipate the shape of an API response, hence we cannot rely on TypeScripts type checking and need to do this manually.

interface Car {

Promise Error Handling

Errors can be handled in a synchronouse fashion
You can throw an exception in a Promise
You can reject a promise with an exception
You can catch an exception with Promise catch

	<!doctype html>

	<html lang="en">
	<head>
	<meta charset="utf-8">

	<title></title>
	<meta name="description" content="">
	<meta name="author" content="Thomas Junghans">

	function log(value, label = "-") {
	console.log(" ");
	console.log(" ");
	console.log(label, JSON.stringify(value, null, " "));
	}