{"rowid": 195, "title": "Levelling Up for Junior Developers", "contents": "If you are a junior developer starting out in the web industry, things can often seem a little daunting. There are so many things to learn, and as soon as you\u2019ve learnt one framework or tool, there seems to be something new out there.\nI am lucky enough to lead a team of developers building applications for the web. During a recent One to One meeting with one of our junior developers, he asked me about a learning path and the basic fundamentals that every developer should know. After a bit of digging around, I managed to come up with a (not so exhaustive) list of principles that was shared with him.\n\nIn this article, I will share the list with you, and hopefully help you level up from junior developer and become a better developer all round. This list doesn\u2019t focus on an particular programming language, but rather coding concepts as a whole. The idea behind this list is that whether you are a front-end developer, back-end developer, full stack developer or just a curious one, these principles apply to everyone that writes code. \nI have tried to be technology agnostic, so that you can use these tips to guide you, whatever your tech stack might be.\nWithout any further ado and in no particular order, let\u2019s get started.\nRefactoring code like a boss\nThe Boy Scouts have a rule that goes \u201calways leave the campground cleaner than you found it.\u201d This rule can be applied to code too and ensures that you leave code cleaner than you found it. As a junior developer, it\u2019s almost certain that you will either create or come across older code that could be improved. The resources below are a guide that will help point you in the right direction.\n\nMy favourite book on this subject has to be Clean Code by Robert C. Martin. It\u2019s a must read for anyone writing code as it helps you identify bad code and shows you techniques that you can use to improve existing code.\nIf you find that in your day to day work you deal with a lot of legacy code, Improving Existing Technology through Refactoring is another useful read.\nDesign Patterns are a general repeatable solution to a commonly occurring problem in software design. My friend and colleague Ranj Abass likes to refer to them as a \u201ccommon language\u201d that helps developers discuss the way that we write code as a pattern. My favourite book on this subject is Head First Design Patterns which goes right back to the basics. Another great read on this topic is Refactoring to Patterns.\nWorking Effectively With Legacy Code is another one that I found really valuable.\n\nImproving your debugging skills\nA solid understanding of how to debug code is a must for any developer. Whether you write code for the web or purely back-end code, the ability to debug will save you time and help you really understand what is going on under the hood.\n\nIf you write front-end code for the web, one of my favourite resources to help you understand how to debug code in Chrome can be found on the Chrome Dev Tools website. While some of the tips are specific to Chrome, these techniques apply to any modern browser of your choice.\nAt Settled, we use Node.js for much of our server side code. Without a doubt, our most trusted IDE has to be Visual Studio Code and the built-in debuggers are amazing. Regardless of whether you use Node.js or not, there are a number of plugins and debuggers that you can use in the IDE. I recommend reading the website of your favourite IDE for more information. \nAs a side note, it is worth mentioning that Chrome Developer Tools actually has functionality that allows you to debug Node.js code too. This makes it a seamless transition from front-end code to server-side code debugging.\nThe Debugging Mindset is an informative online article by Devon H. O\u2019Dell and discusses the the psychology of learning strategies that lead to effective problem-solving skills. \n\nA good understanding of relational databases and NoSQL databases\nAlmost all developers will need to persist data at some point in their career. Even if you don\u2019t write SQL queries in your day to day job, a solid understanding of how they work will help you become a better developer.\n\nIf you are a complete newbie when it comes to databases, I recommend checking out Code Academy. They offer a free online course that can help you get your head around how relational databases work. The course is quite basic, but is a useful hands-on approach to learning this topic.\nThis article provides a great explainer for the difference between the SQL and NoSQL databases, and this  Stackoverflow answer goes a little deeper into the subject of the two database types.\nIf you\u2019d like to learn more about NoSQL queries, I would recommend starting with this article on MongoDB queries. Unfortunately, there isn\u2019t one overall course as most NoSQL databases have their own syntax. \n\nYou may also have noticed that I haven\u2019t included other types of databases such as Graph or In-memory; it\u2019s worth focussing on the basics before going any deeper.\nPerformance on the web\nIf you build for the web today, it is important to understand how the browser receives and renders the content that you send it. I am pretty passionate about Web Performance, and hope that everyone can learn how to make websites faster and more efficient. It can be fun at the same time!\n\nSteve Souders High Performance Websites is the godfather of web performance books. While it was created a few years ago and many of the techniques might have changed slightly, it is the original book on the subject and set up many of the ground rules that we know about web performance today.\nA free online resource on this topic is the Google Developers website. The site is an up to date guide on the best web performance techniques for your site. It is definitely worth a read.\nThe network plays a key role in delivering data to your users, and it plays a big role in performance on the web. A fantastic book on this topic is Ilya Grigorik\u2019s High Performance Browser Networking. It is also available to read online at hpbn.co.\n\nUnderstand the end to end architecture of your software project\nI find that one of the best ways to improve my knowledge is to learn about the architecture of the software at the company I work at. It gives you a good understanding as to why things are designed the way they are, why certain decisions were made, and gives you an understanding of how you might do things differently with hindsight.\nTry and find someone more senior, such as a Technical Lead or Software Architect, at your company and ask them to explain the overall architecture and draw a few high-level diagrams for you. Not to mention that they will be impressed with your willingness to learn.\n\nI recommend reading Clean Architecture: A Craftsman\u2019s Guide to Software Structure and Design for more detail on this subject.\nFar too often, software projects can be over-engineered and over-architected, it is worth reading Just Enough Software Architecture. The book helps developers understand how the smallest of changes can affect the outcome of your software architecture.\n\nHow are things deployed\nA big part of creating software is actually shipping it! How is the software at your company released into the wild? Does your company do Continuous Integration? Continuous Deployment?\n\nEven if you answered no to any of these questions, it is worth finding someone with the knowledge in your company to explain these things to you. If it is not already documented, perhaps you could start a wiki to document everything you\u2019re learning about the system - this is a great way to level up and be appreciated and invaluable.\nA streamlined deployment process is a beautiful thing, and understanding how they work can help you grow your knowledge as a developer. \nContinuous Integration is a practical read on the ins and outs of implementing this deployment technique.\nDocker is another great tool to use when it comes to software deployment. It can be tricky at first to wrap your head around, but it is definitely worth learning about this great technology. The documentation on the website will teach and guide you on how to get started using Docker.\n\nWriting Tests\nTesting is an essential tool in the developer bag of skills. They help you to make big refactoring changes to your code, and feel a lot more confident knowing that your changes haven\u2019t broken anything. There are so many benefits to testing, which make it so important for developers at every level to become acquainted with it/them.\n\nThe book that started it all for me was Roy Osherove\u2019s The Art of Unit Testing. The code in the book is written in C#, but the principles apply to every language. It\u2019s a great, easy-to-understand read.\nAnother great read is How Google Tests Software and covers exactly what it says on the tin. It covers many different testing techniques such as exploratory, black box, white box, and acceptance testing and really helps you understand how large organisations test their code.\n\nSoft skills\nWhilst reading through this article, you\u2019ve probably noticed that a large chunk of it focusses on code and technical ability. Without a doubt, I\u2019d say that it is even more important to be a good teammate. If you look up the definition of soft skills in the dictionary, it is defined as \u201cpersonal attributes that enable someone to interact effectively and harmoniously with other people\u201d and I think that it sums this up perfectly. Working on your \u201csoft skills\u201d is something that can truly help you level up in your career. You may be the world\u2019s greatest coder, but if you colleagues can\u2019t get along with you, your coding skills won\u2019t matter!\nWhile you may not learn how to become the perfect co-worker overnight, I really try and live by the motto \u201cdon\u2019t be an arsehole\u201d. Think about how you like to be treated and then try and treat your co-workers with the same courtesy and respect. The next time you need to make a decision at work, ask yourself \u201cis this something an arsehole would do\u201d? If you answered yes to that question, you probably shouldn\u2019t do it!\nSummary\nLevelling up as a junior developer doesn\u2019t have to be scary. Focus on the fundamentals and they should hold you in good stead, regardless of the new things that come along. Software engineering is built on these great principles that have stood the test of time.\nWhilst researching for this article, I came across a useful Github repo that is worth mentioning. Things Every Programmer Should Know is packed with useful information. I have to admit, I didn\u2019t know everything on there!\nI hope that you have found this list helpful. Some of the topics I have mentioned might not be relevant for you at this stage in your career, but should give a nudge in the right direction. After all, knowledge is power!\nIf you are a junior developer reading this article, what would you add to it?", "year": "2017", "author": "Dean Hume", "author_slug": "deanhume", "published": "2017-12-05T00:00:00+00:00", "url": "https://24ways.org/2017/levelling-up-for-junior-developers/", "topic": "code"}
{"rowid": 309, "title": "HTTP/2 Server Push and Service Workers: The Perfect Partnership", "contents": "Being a web developer today is exciting! The web has come a long way since its early days and there are so many great technologies that enable us to build faster, better experiences for our users. One of these technologies is HTTP/2 which has a killer feature known as HTTP/2 Server Push.\nDuring this year\u2019s Chrome Developer Summit, I watched a really informative talk by Sam Saccone, a Software Engineer on the Google Chrome team. He gave a talk entitled Planning for Performance, and one of the topics that he covered immediately piqued my interest; the idea that HTTP/2 Server Push and Service Workers were the perfect web performance combination.\n\nIf you\u2019ve never heard of HTTP/2 Server Push before, fear not - it\u2019s not as scary as it sounds. HTTP/2 Server Push simply allows the server to send data to the browser without having to wait for the browser to explicitly request it first. In this article, I am going to run through the basics of HTTP/2 Server Push and show you how, when combined with Service Workers, you can deliver the ultimate in web performance to your users.\nWhat is HTTP/2 Server Push?\nWhen a user navigates to a URL, a browser will make an HTTP request for the underlying web page. The browser will then scan the contents of the HTML document for any assets that it may need to retrieve such as CSS, JavaScript or images. Once it finds any assets that it needs, it will then make multiple HTTP requests for each resource that it needs and begin downloading one by one. While this approach works well, the problem is that each HTTP request means more round trips to the server before any data arrives at the browser. These extra round trips take time and can make your web pages load slower. \nBefore we go any further, let\u2019s see what this might look like when your browser makes a request for a web page. If you were to view this in the developer tools of your browser, it might look a little something like this:\n\nAs you can see from the image above, once the HTML file has been downloaded and parsed, the browser then makes HTTP requests for any assets that it needs. \nThis is where HTTP/2 Server Push comes in. The idea behind HTTP/2 Server Push is that when the browser requests a web page from the server, the server already knows about all the assets that are needed for the web page and \u201cpushes\u201d it to browser. This happens when the first HTTP request for the web page takes place and it eliminates an extra round trip, making your site faster. \nUsing the same example above, let\u2019s \u201cpush\u201d the JavaScript and CSS files instead of waiting for the browser to request them. The image below gives you an idea of what this might look like.\n\nWhoa, that looks different - let\u2019s break it down a little. Firstly, you can see that the JavaScript and CSS files appear earlier in the waterfall chart. You might also notice that the loading times for the files are extremely quick. The browser doesn\u2019t need to make an extra HTTP request to the server, instead it receives the critical files it needs all at once. Much better! \nThere are a number of different approaches when it comes to implementing HTTP/2 Server Push. Adoption is growing and many commercial CDNs such as Akamai and Cloudflare already offer support for Server Push. You can even roll your own implementation depending on your environment. I\u2019ve also previously blogged about building a basic HTTP/2 Server Push example using Node.js. In this post, I\u2019m not going to dive into how to implement HTTP/2 Server Push as that is an entire post in itself! However, I do recommend reading this article to find out more about the inner workings.\nHTTP/2 Server Push is awesome, but it isn\u2019t a magic bullet. It is fantastic for improving the load time of a web page when it first loads for a user, but it isn\u2019t that great when they request the same web page again. The reason for this is that HTTP/2 Server Push is not cache \u201caware\u201d. This means that the server isn\u2019t aware about the state of your client. If you\u2019ve visited a web page before, the server isn\u2019t aware of this and will push the resource again anyway, regardless of whether or not you need it. HTTP/2 Server Push effectively tells the browser that it knows better and that the browser should receive the resources whether it needs them or not. In theory browsers can cancel HTTP/2 Server Push requests if they\u2019re already got something in cache but unfortunately no browsers currently support it. The other issue is that the server will have already started to send some of the resource to the browser by the time the cancellation occurs.\nHTTP/2 Server Push & Service Workers\nSo where do Service Workers fit in? Believe it or not, when combined together HTTP/2 Server Push and Service Workers can be the perfect web performance partnership. If you\u2019ve not heard of Service Workers before, they are worker scripts that run in the background of your website. Simply put, they act as middleman between the client and the browser and enable you to intercept any network requests that come and go from the browser. They are packed with useful features such as caching, push notifications, and background sync. Best of all, they are written in JavaScript, making it easy for web developers to understand.\nUsing Service Workers, you can easily cache assets on a user\u2019s device. This means when a browser makes an HTTP request for an asset, the Service Worker is able to intercept the request and first check if the asset already exists in cache on the users device. If it does, then it can simply return and serve them directly from the device instead of ever hitting the server.\nLet\u2019s stop for a second and analyse what that means. Using HTTP/2 Server Push, you are able to push critical assets to the browser before the browser requests them. Then, using Service Workers you are able to cache these resources so that the browser never needs to make a request to the server again. That means a super fast first load and an even faster second load!\nLet\u2019s put this into action. The following HTML code is a basic web page that retrieves a few images and two JavaScript files.\n<!DOCTYPE html>\n<html>\n<head>\n  <meta charset=\"UTF-8\">\n  <title>HTTP2 Push Demo</title>\n</head>\n<body>\n  <h1>HTTP2 Push</h1>\n  <img src=\"./images/beer-1.png\" width=\"200\" height=\"200\" />\n  <img src=\"./images/beer-2.png\" width=\"200\" height=\"200\" />\n  <br>\n  <br>\n  <img src=\"./images/beer-3.png\" width=\"200\" height=\"200\" />\n  <img src=\"./images/beer-4.png\" width=\"200\" height=\"200\" />\n  <!-- Scripts -->\n  <script async src=\"./js/promise.min.js\"></script>\n  <script async src=\"./js/fetch.js\"></script>\n  <script>\n  // Register the service worker\n  if ('serviceWorker' in navigator) {\n    navigator.serviceWorker.register('./service-worker.js').then(function(registration) {\n      // Registration was successful\n      console.log('ServiceWorker registration successful with scope: ', registration.scope);\n    }).catch(function(err) {\n      // registration failed :(\n      console.log('ServiceWorker registration failed: ', err);\n    });\n  }\n  </script>\n</body>\n</html>\nIn the HTML code above, I am registering a Service Worker file named service-worker.js. In order to start caching assets, I am going to use the Service Worker toolbox . It is a lightweight helper library to help you get started creating your own Service Workers. Using this library, we can actually cache the base web page with the path /push.\nThe Service Worker Toolbox comes with a built-in routing system which is based on the same routing as Express. With just a few lines of code, you can start building powerful caching patterns.\nI\u2019ve add the following code to the service-worker.js file.\n(global => {\n  'use strict';\n\n  // Load the sw-toolbox library.\n  importScripts('/js/sw-toolbox/sw-toolbox.js');\n\n  // The route for any requests\n  toolbox.router.get('/push', global.toolbox.fastest);\n\n  toolbox.router.get('/images/(.*)', global.toolbox.fastest);\n\n  toolbox.router.get('/js/(.*)', global.toolbox.fastest);\n\n  // Ensure that our service worker takes control of the page as soon as possible.\n  global.addEventListener('install', event => event.waitUntil(global.skipWaiting()));\n  global.addEventListener('activate', event => event.waitUntil(global.clients.claim()));\n})(self);\nLet\u2019s break this code down further. Around line 4, I am importing the Service Worker toolbox. Next, I am specifying a route that will listen to any requests that match the URL /push. Because I am also interested in caching the images and JavaScript for that page, I\u2019ve told the toolbox to listen to these routes too.\nThe best thing about the code above is that if any of the assets exist in cache, we will instantly return the cached version instead of waiting for it to download. If the asset doesn\u2019t exist in cache, the code above will add it into cache so that we can retrieve it when it\u2019s needed again.\nYou may also notice the code global.toolbox.fastest - this is important because gives you the compromise of fulfilling from the cache immediately, while firing off an additional HTTP request updating the cache for the next visit.\nBut what does this mean when combined with HTTP/2 Server Push? Well, it means that on the first load of the web page, you are able to \u201cpush\u201d everything to the user at once before the browser has even requested it. The Service Worker activates and starts caching the assets on the users device. The next time a user visits the page, the Service Worker will intercept the request and serve the asset directly from cache. Amazing! \nUsing this technique, the waterfall chart for a repeat visit should look like the image below.\n\nIf you look closely at the image above, you\u2019ll notice that the web page returns almost instantly without ever making an HTTP request over the network. Using the Service Worker library, we cached the base page for the route /push, which allowed us to retrieve this directly from cache.\nWhether used on their own or combined together, the best thing about these two features is that they are the perfect progressive enhancement. If your user\u2019s browser doesn\u2019t support them, they will simply fall back to HTTP/1.1 without Service Workers. Your users may not experience as fast a load time as they would with these two techniques, but it would be no different from their normal experience. HTTP/2 Server Push and Service Workers are really the perfect partners when it comes to web performance.\nSummary\nWhen used correctly, HTTP/2 Server Push and Service Workers can have a positive impact on your site\u2019s load times. Together they mean super fast first load times and even faster repeat views to a web page. Whilst this technique is really effective, it\u2019s worth noting that HTTP/2 push is not a magic bullet. Think about the situations where it might make sense to use it and don\u2019t just simply \u201cpush\u201d everything; it could actually lead to having slower page load times. If you\u2019d like to learn more about the rules of thumb for HTTP/2 Server Push, I recommend reading this article for more information. \nAll of the code in this example is available on my Github repo - if you have any questions, please submit an issue and I\u2019ll get back to you as soon as possible. \nIf you\u2019d like to learn more about this technique and others relating to HTTP/2, I highly recommend watching Sam Saccone\u2019s talk at this years Chrome Developer Summit. \nI\u2019d also like to say a massive thank you to Robin Osborne, Andy Davies and Jeffrey Posnick for helping me review this article before putting it live!", "year": "2016", "author": "Dean Hume", "author_slug": "deanhume", "published": "2016-12-15T00:00:00+00:00", "url": "https://24ways.org/2016/http2-server-push-and-service-workers/", "topic": "code"}