DRY is really a philosophy that says do it once, and do it so that it captures ALL information where it belongs, and is NOT repeated elsewhere. Here is the code. It's simple, yet very powerful, and the number of ways that it can be used are almost limitless. Solution 3: Automate the repetition of code and design using some form of code generation. ng-container actually does nothing, but this is why it is so useful. But, the DRY principle applies to the duplication of business logic, not the duplication of "code". I am currently stuck trying to apply the DRY principle in this scenario. Log in Create account DEV is a community of ... Don't repeat yourself principle ( DRY ) If we didn’t want to use a div, we could have used a ng-container element. Undoubtedly the most common manifestation of the DRY principle is the creation of a function for re-used logic. You’ll also struggle repeatedly with defining what the “one thing” you want to do is. But what if you want to pass some HTML content to the child component, for example some content with an image or a link? When rendering the component, will be replaced by whatever you have written between the child component’s tags in the parent component. At work, we use Angular’s UI Grid component to display tabular data. Meaning, the developer sees the same (or similar) series of tokens, references, and operators and they believe that this represents "duplication". Dryv will generate JavaScript for client-side validation. JavaScript; Khanh Nguyen. You can use ng-content to pass whatever content you want to the error card. DRY usually refers to code duplication. DRY programming is very useful, especially in big applications where code is constantly maintained, changed … In parent components using the error card component, we can create a template for the error, in the example below we created one with a div and a link a. Tagged with javascript, php, functional. The DRY principle is one of the oldest and best-known software design principles, and employing it makes your code much easier to edit and scale. Not really. Active 3 years, 9 months ago. By helping us applying the DRY principle (Don’t Repeat Yourself), they make frontend code less error-prone and easier to maintain. We are using the defaultTemplate reference of the template as the value of ngTemplateOutlet in order to instantiate the template inside the div. In other words avoiding the repetition of any part of a system is a desirable trait. Had to edit the code a bit to make it fit my specs, but this is the perfect answer to my problem! How I Got Rid of State Observables in Angular, How To Check for an Undefined/Null/Empty String, Angular + Font Awesome in 5 Easy Steps With angular-fontawesome. You could also add a new @Input for a link or for the url of the image. It gets rendered only when used. 1. (max 2 MiB). [The DRY] principle is similar to OnceAndOnlyOnce, but with a different objective. Pastebin is a website where you can store text online for a set period of time. HTML. Here’s an example of the DRY principle in action. Let’s say Facebook’s entire website is made up of only one function called runFacebook(). This element is not rendered, but its content is and you can attach a structural directive to it. The DRY principle is aimed at reducing repetition and boilerplate in the software by forming abstractions. We can now combine all this into a solution to our error card problem. The DRY principle is simply “Don’t Repeat Yourself”. It refers to the smallest parts of your software.When you are building a large software project, you will usually be overwhelmed by the overall complexity. Overview. Don’t Repeat Yourself is the principle that any code in your program should only be written once, and never duplicated. We will use it with the ngTemplateOutlet directive. The trap here is that the developer inappropriately applies the DRY principle to "syntax". KISS: Keep It Simple Stupid. The function would still do one huge thin… CodeHS Glossary. https://stackoverflow.com/questions/35243353/apply-dry-principle-with-javascript/35243483#35243483. With ng-container you can have a template element to apply the second strucutral directive to but this element itself is not rendered, it is not displayed in the DOM (but its content is). Essentially, you do not want to have code that repeats itself. DRY is often a poorly understood principle because it is constantly confused with code-reuse. You’ll be surprised at the number of times you would like your function to do more than “one thing”. I am currently stuck trying to apply the DRY principle in this scenario. Posted on 14 November, 2018 in Others | Updated on 14 November, 2018. https://stackoverflow.com/questions/35243353/apply-dry-principle-with-javascript/35243816#35243816. Don't repeat yourself ( DRY, or sometimes do not repeat yourself) is a principle of software development aimed at reducing repetition of software patterns, replacing it with abstractions or using data normalization to avoid redundancy. Apply DRY principle with JavaScript - i stuck trying apply dry principle in scenario. Apply DRY principle with JavaScript. Here is the code. This principle should be practiced within logical components, as well as, documentation of code. You might think the DRY Principle comes down to not writing … A design principle originating from the U.S. Navy that goes back to 1960 already. View All . Views: 465. The DRY principle should be applied to the how-to's, whereas the DAMP principle should be applied to the what-to's. On its own, the template, that is to say the tag and its content, is not rendered. The DRY Principle (Don’t Repeat Yourself), as this is called, is like the Golden Rule: it has endless and varied applications and is — all by itself — enough to make you a Very Good Person. As such, even though the initial question on our Slack channel was about how to keep your JavaScript / TypeScript code clean, X-Teamers replied with some of the general design principles of clean code. Any pointers? The idea behind the Don’t-Repeat-Yourself (DRY) design principle is an easy one: a piece of logic should only be represented once in an application. According to Rick Anderson, "One of the design tenets of MVC is DRY ("Don't Repeat Yourself")" and "The validation support provided by MVC and Entity Framework Core Code First is a good example of the DRY principle in action. Pastebin.com is the number one paste tool since 2002. ngTemplateOutlet is a directive enabling us to instantiate an Angular template. 0. By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Service. Since ea… Every function you write should do exactly one thing. Another solution, this one enabling us to give our error a default value, is to use an ng-template and an ng-container with the ngTemplateOutlet attribute. You could create a special component for such a case, but that would require you to copy the styling (repeating yourself). For example, let’s make a component to display error messages: To pass a simple error text to the component, you would use an @Input. The DRY (Don’t Repeat Yourself) principle it basically consist in the following: Every piece of knowledge must have a single, unambiguous, authoritative representation within a system. According to the principle: When it comes to OOP, this means utilizing abstract classes, interfaces, and public constants. In other words, you should describe the scenario steps as expressively as possible, but you can (and should) extract any implementation details regarding those steps and reuse them between tests. I have used switch because day may be diff value. It follows the same principle from above. The error card component renders the passed template if there is one, otherwise uses its default template. I hope this article helped you understand how you can combine them to reuse components with different types of content. Otherwise known as Don’t Repeat Yourself, this principle is designed to help eliminate repeated code and reduce the complexity of a solution. On the other hand, when the DRY principle is not followed, this is known as WET solutions, which stands for either Write Everything Twice or We Enjoy Typing. You are switching on a variable to set another variable to the value of the same variable. Click here to upload your image The second problem is that looping through the "database" object may not be the most efficient solution, especially since … DRY refers to code writing methodology. It should have one clearly defined goal. Whenever there's a functionality common across classes, it either might make sense to abstract them away into a common parent class or use interfaces to couple their functionality: Both a Cat and a Dog need to eat food, but they speak differently. here code. This is because they are so natural in JavaScript, so easy to create, and so pervasive in tutorials and API documentation. Follow. The DRY Principle: Don't Repeat Yourself DRY stand for "Don't Repeat Yourself," a basic principle of software development aimed at reducing repetition … It is commonly used with an *ngIf directive: We are going to use it here with an ng-container having a ngTemplateOutlet attribute. But in both cases, creating a new type of error message with a new type of content would whether require you to create yet another component, repeating yourself again, or adding another @Input. Very similar to Unix’s “Do one thing and do it well”. The Don't Repeat Yourself(DRY) principle is a common principle across programming paradigms, but it is especially important in OOP. Thankfully Ansible has a method to help with DRY, and that is variables. Between the tags of the second error card though, we have added some text, a div and a link. Our error card component has a default template for the error with the reference defaultTemplate. If you find that you are writing a file path, URL, IP address, setting etc… multiple times then a method should be used to replace those multiple instances with one instance that is referenced. Introduction. I am currently trying to sharpen my refactoring skills, I have a block of code that I have written that has two methods that are very similar, and I am trying to wrap my head around simplifying my JavaScript is one of the most widely used languages in web development. By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy, 2020 Stack Exchange, Inc. user contributions under cc by-sa. can see, trying run scripts containing different variables on different days. A component is written once but can be used over and over again, whether by manually using its selector at different places or by using Angular structural directives like *ngFor. Humans are not goo… Nowadays there are very powerful code generator frameworks out there. pointers? Actually, they are more than one. The “rule of 3” is a good shorthand for identifying when you might want to rethink how your code is organized– “You should consider writing a function whenever you’ve copied and pasted a block of code more than twice (i. You could give a default value to the property, An unexpected error occurred for example, that would be displayed in the cases where you don’t pass any text to the child component. Turtle. You can’t attach two structural directives to the same element: You could add a div element but it would not be used for anything except to fix your double directive problem and it could even break your layout. This principle is so important to understand, that I won't write it twice! The idea behind the Don't-Repeat-Yourself (DRY) design principle is an easy one: a piece of logic should only be represented In this ahort series on DRY I'll concentrate on the 'logic' side of DRY. As you can see, I am trying to run scripts containing different variables on different days. JavaScript. I suggest that object literals are possibly the most frequent violators of the DRY Principle. Another outcome of DRY is “code IS your documentation”. Ask Question Asked 3 years, 9 months ago. I mean, I could simply shoot out a bunch of else if statements until Friday, but that just does not seem like the right way to do things. For instance, when making a web page the code for your navigation bar may repeat itself on every single web page you have for your site. There is a better way. You can also provide a link from the web. ng-template lets you define an Angular template. Giving the output: That code is repetitive, and can be refactored (re-written while maintaining the same functionality) to this: Giving the same output: The refactored version actually uses more code tha… You often need to pass data from a parent to a child component. Karel. DRY principle in programming. The DRY code philosophy is stated as “Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.” As you can see, I am trying to run scripts containing different variables on different days. If we write the same logic more than once, we should “DRY up our code.” A common way to DRY up code is to wrap our duplicated logic with a function and replace all places it appears with function calls. These directives, ng-content, ng-template and ng-container help you create reusable customisable components. DRY principle (Don’t Repeat Yourself) is a principle that every programmer needs to understand and follow. The Single Authority afforded by the DRY principle and the duplication of the source as a basis for the program environment adds inertia to the system (see RedundancyIsInertia) for the sake of its stability.Here's a little list that I believe shows how RedundancyIsInertia, the DRY principle, OnceAndOnlyOnce, and testing should work together: . The DRY principle is stated as "Every piece of knowledge must have a single, unambiguous, authoritative representation within a system." We can then pass this template as an input to the error card component. Skip to content. I love Java and everything related to Java. Here are 10 tips from well-respected web developers within the JavaScript community. The Don't-Repeat-Yourself (DRY) design principle in .NET Part 1 , Tips and tricks in C# . The DRY principle states: Every piece of knowledge must have a single, unambiguous, authoritative representation within a system. This works as long as the data you want to pass to the child component is a JavaScript value (a string, an object, a number, …). By helping us applying the DRY principle (Don’t Repeat Yourself), they make frontend code less error-prone and easier to maintain. mean, shoot out bunch of else if statements until friday, not seem right way things. That's why it's so important to gather advice from those who have gone before you. It's commonly referred to by the acronym, DRY, and came up in the book The Pragmatic Programmer, by Andy Hunt and Dave Thomas, but the concept, itself, has been known for a long time. Example (with code repetition): DRY Example: Good code is DRY code. Components are independent and easily reusable. However the Once and Only Once principle is slightly different. I felt like I repeated myself a couple of times, and wondering if that can be avoided. ng-content works as a placeholder. Viewed 583 times 1. Do not let these innocent-looking constructs take you in! OOP started as a way to allow dynamic objects encapsulate their behavior and to communicate by means of messages and message routing (or dispatching). The DRY (Don’t Repeat Yourself) is a software development principle, which has been formulated by Andy Huntand Dave Thomasin their book The Pragmatic Programmer. In the example above, we haven’t given any content to the first error card, it will stay empty. If the only difference between each day is the tuePhp/monPhp values, can you not wrap it up in a function and pass those as an argument? One being that I believe that I didn't follow the DRY principle to the fullest. They will be displayed inside the error card, replacing the : But there is no default value anymore and giving one would be pretty tricky (not impossible, but tricky). The DRY Principle - Don't Repeat Yourself The DRY Priciple, which stands for Don't Repeat Yourself, is a principle used in computer science. 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The second error card problem apply the DRY principle its content, not... Are almost limitless different days comprehend but harder to implement what the one..., yet very powerful code generator frameworks out there run scripts containing different variables on different days of ways it! Given any content to the error with the reference defaultTemplate haven ’ t given any content to the:... Grid component to display tabular data to instantiate the template, that is variables can! Of code and design using some form of code and design using some of... The Once and only Once principle is simply “ Don ’ t given content... Component has a method to help with DRY, and wondering if that can be are! Be surprised at the number of ways that it can be dry principle in javascript are almost limitless tips and in! Worry is about having to hand-code repetitions of patterns and designs since hand-coding code/design... Example of the second error card problem use ng-content to pass data from a to. Can now combine all this into a Solution to our error card.. Being that i did n't follow the DRY principle should be applied to the duplication of business logic not!