Web developer's learning journal
In this post, I’ll record how to do error handling for multiple async calls in JavaScript. This may seem a simple topic, but I often struggled with this when I first learned about JavaScript. Before doing so, I’d like to quickly go over chained Promises and async/await in JavaScript. Chained Promise calls (“Why don’t you …
In this post, I’ll show you all the technical questions I received in interviews for front end developer positions with React.js. Interview questions What is the state in React, and when is it useful? The state in a React component is a JavaScript object, which stores the state of the component. States are useful when …
In this post, I’ll write about how to configure Laravel apps for PHPUnit, and how to write basic tests. This post is meant to be a note for myself, but hopefully someone finds it helpful too. Configuration Firstly, configure phpunit.xml in order to use in-memory SQLite DB. The objective is to have PHPUnit create mock …
Recently I decided to teach myself AWS, but I soon started to wonder why and when to use AWS EC2 rather than renting a server from a conventional server provider. Why? the main reasons are… EC2 seems so convoluted with many acronyms and terms (e.g. AMI, ESB, EFS), all of which makes it difficult to …
If you’ve used Nginx, you may have come across this error. 2019/04/12 06:43:24 [error] 11365#0: *257 upstream sent too big header while reading response header from ups tream, client: 127.0.0.1, server: hiroki-example.com, request: “POST /payment HTTP/1.1”, upstream: “fastcgi://127.0.0.1:9000”, host: “hiroki-example.com”, referrer: “http://hiroki-example.com/payment” I’ve seen this many times, but haven’t really tried to understand it deeply. In …
When testing wit Jest, the test is working in a command line environment, which mimics the browser. However, this fake browser environment doesn’t allow us to interact with APIs outside of it. Then, how do we make AJAX requests while testing with Jest? Assuming that you use axios for calling API calls, moxios will be the …
I’ve been teaching myself how to write tests for React app. It seems that Enzyme is the de facto standard for it. Here is what I’ve learned for testing components with form elements (e.g. <input />). Setting up First of all, install the modules. npm install –save enzyme enzyme-adapter-react-16 NOTE: It depends on the version …
Draw a component treemap with basic component structures The first step to take is to draw a rough idea as to how the whole app will look like. Typically, you either… get a design plan from your client or designer. Or, develop a design plan by yourself Based on the design, you are going to …
1. Definition It provides an interface for creating families of related or dependent objects without specifying their concrete classes. 2. Case study 2.1 The problem You’re creating a car manufacturer simulator, where you can simulate the process of manufacturing cars. As you may know, petrol cars and diesel cars need different parts in their fuel systems, …