Recently, I published a react component to npm that renders a file tree React component in a native Electron application. It was a fun project, and pretty comprehensive, covering basic computer science techniques through advanced front-end frameworks, so I thought it would be a good topic to share. Also, in examples, I have left out import statements to keep things simple. Good question. Why did I make this component?
At the end of the program, students complete a comprehensive capstone project that showcases their skill as developers and usually includes a few new techniques that they picked up to make the project great.
My group and I decided to make a desktop application that would allow developers to pair program together remotely from anywhere. You can find the deployed project here. The app features peer to peer video, command line Git functionality for version control, and a live updating code editor.
Alongside the code editor we wanted a responsive file tree view that would expand and contract when a user entered or closed a directory.
So, how do we populate this object? Well, to start things off, we need a root directory, and access to the files and folders inside that directory. How do we get that? The first thing we need to do is get a list of all files and folders. Because this method and most other fs methods are asynchronous, it would be nice if we could get these into a promise for more legible code flow and better error handling. So, our readdir function becomes fs.
How can we tell if a something is a file or a folder? Well, the fs library provides us a method that gives meta data about a file, given a file path. Its the stat method, and one of the bits of data it provides is a boolean, returned from an isFile method invocation. It will return true for a file, and false for a directory. OK, now for the hard part. Remember that folders can have folders inside them, and those folders can have folders inside them, and those folders can have….
Recall the definition of recursion:. Recursion in computer science is a method where the solution to a problem depends on solutions to smaller instances of the same problem as opposed to iteration. Concrete Mathematics. Chapter 1: Recurrent Problems. Discrete Mathematics with Applications 2nd ed. That sounds like exactly what we need to do! Side note: recursive solutions typically depend on 2 cases: a recursive case, in which we recall our function, and a base case, in which we advance towards a terminating condition.
This is what prevents us from exceeding our maximum call stack size.Context provides a way to pass data through the component tree without having to pass props down manually at every level. In a typical React application, data is passed top-down parent to child via props, but this can be cumbersome for certain types of props e. Context provides a way to share values like these between components without having to explicitly pass a prop through every level of the tree.
Context is primarily used when some data needs to be accessible by many components at different nesting levels. Apply it sparingly because it makes component reuse more difficult.
If you only want to avoid passing some props through many levels, component composition is often a simpler solution than context. For example, consider a Page component that passes a user and avatarSize prop several levels down so that deeply nested Link and Avatar components can read it:. It might feel redundant to pass down the user and avatarSize props through many levels if in the end only the Avatar component really needs it. This inversion of control can make your code cleaner in many cases by reducing the amount of props you need to pass through your application and giving more control to the root components.
This pattern is sufficient for many cases when you need to decouple a child from its immediate parents. You can take it even further with render props if the child needs to communicate with the parent before rendering. However, sometimes the same data needs to be accessible by many components in the tree, and at different nesting levels.
Common examples where using context might be simpler than the alternatives include managing the current locale, theme, or a data cache. Creates a Context object. When React renders a component that subscribes to this Context object it will read the current context value from the closest matching Provider above it in the tree. The defaultValue argument is only used when a component does not have a matching Provider above it in the tree.
This can be helpful for testing components in isolation without wrapping them. Note: passing undefined as a Provider value does not cause consuming components to use defaultValue.
Every Context object comes with a Provider React component that allows consuming components to subscribe to context changes.
Accepts a value prop to be passed to consuming components that are descendants of this Provider. One Provider can be connected to many consumers. Providers can be nested to override values deeper within the tree.
The propagation from Provider to its descendant consumers including. Changes are determined by comparing the new and old values using the same algorithm as Object.
Practical Recursion: Implementing a File Tree View in React & Electron
The way changes are determined can cause some issues when passing objects as value : see Caveats.In this article we will quickly build a dynamic form based on json data with events and states. As usual spin a new react project using whatever template you prefer.
I will be using create-react-app. Once the project is setup change the directory to the folder and exeucte the below command. Open the code in your favorite editor, shrug your shoulder off and get coding.
Open up App. In the above block of code we are defining some state information. Continue working on App. Let us have a deep look at the model props as that is the heart of this dynamic form component. Now comes the crux of the code, the DynamicForm, itself. Now I have created a folder with the following hierarchy. Inside DynamicForm folder, all the code for the components resides in index.
For simplicity I would not bother putting the styles here but you can always refer the github for the same.
Ok, we begin by creating an empty state variable.
Any guess, why state is empty? Yes, because state will be created dynamically by using the keys from the model props. We begin by storing the title in a variable and then return the jsx for the component.
The returned jsx is very simple, except the form has a submit handler and the important things are happening in the helper method renderForm. Huh, the method is not as complex as we might think. We begin my storing the model props in a variable.
We grab some key props from the model for ease of use. Finally we return a jsx. The code is annotated with my illegible handwriting, but I hope it makes it clear the intent of the code.This project was bootstrapped with Create React App. Below you will find some information on how to perform common tasks. You can find the most recent version of this guide here. In most cases bumping the react-scripts version in package.
We commit to keeping the breaking changes minimal so you can upgrade react-scripts painlessly. We are always open to your feedback.
Subscribe to RSS
You may create subdirectories inside src. For faster rebuilds, only files inside src are processed by Webpack. You can, however, create more top-level directories. They will not be included in the production build so you can use them for things like documentation. Runs the app in the development mode. Launches the test runner in the interactive watch mode. See the section about running tests for more information. Builds the app for production to the build folder. It correctly bundles React in production mode and optimizes the build for the best performance.
The build is minified and the filenames include the hashes. Your app is ready to be deployed! Note: this is a one-way operation. This command will remove the single build dependency from your project.
Instead, it will copy all the configuration files and the transitive dependencies Webpack, Babel, ESLint, etc right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. They are not required for linting.
You should see the linter output right in your terminal as well as the browser console. However, if you prefer the lint results to appear right in your editor, there are some extra steps you can do. If you are using the Atom linter-eslint plugin, make sure that Use global ESLint installation option is checked:.
We recognize that this is suboptimal, but it is currently required due to the way we hide the ESLint dependency. The ESLint team is already working on a solution to this so this may become unnecessary in a couple of months. It also includes a set of scripts used by Create React App as a development dependency. You may install other dependencies for example, React Router with npm :.
This project setup supports ES6 modules thanks to Babel. While you can still use require and module. Be aware of the difference between default and named exports. It is a common source of mistakes. We suggest that you stick to using default imports and exports when a module only exports a single thing for example, a component. Named exports are useful for utility modules that export several functions.
A module may have at most one default export and as many named exports as you like.A lightweight and fast control to render a select component that can display hierarchical tree data. A Grid and Tree Component written in React using the Redux Pattern with plenty of open source examples, and an interesting backstory. Supports iterable objects, such as Immutable. Data-Driven, Fast, Efficient and Customisable. React-treeview Easy, light, flexible treeview made with React. It maintains an internal tree structure within the component through js-tree.
Tree A collection of 18 posts. A simple React tree menu component. A React component for Drag-and-drop sortable representation of hierarchical data. A simple react component which renders data as a tree using svg. Customizable Treeviewer built in react for visualizing hierarchical data.
A modern, themable and configurable treeview for React. A simple and elegant checkbox tree for React. A fast, efficient tree table component for ReactJS. React TreeSelect Component. Simple to use, configurable tree view with full support for drop-in animations.
Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I am building a react native application. It's basically just a tree with categories and sub-categories and then pdf documents as below.
The tree with the documents is on a server with an Express web App so running nodeJS. The thing is that we don't know the number of categories, sub-categories and final documents on the tree. So I think we have to build that tree dynamically. Every time we go into a category we could ask the server what's in the folder and display them but I don't know how to achieve that. Learn more.
How To Create React.js Components Dynamically
React native dynamically build a tree Ask Question. Asked 3 months ago. Active 3 months ago. Viewed 47 times. Any ideas? Scuym Scuym 1 2 2 bronze badges. The question is too vague. How do you ask a server what's in a folder? You make an api for it.
Or use a library that spits out an api for it. The question has less to do with react and more to do with whatever software your server is running. Is your server running on node. Too vague. We really need to see what you've coded so far to help. I'm assuming the category structure here but you could get a flat list via API endpoint A then build the tree minus the files using recursion in your UI.
If this was in an accordian style UI component - when the user expands a 'bottom' category you could then call endpoint B which will get you the list of files for said category and update the UI. Thank you.In web pages, sidebars in web pages are amongst one of the most useful components that exist in the page due to their navigational functionality.
Today we will be building a modern sidebar in react using recursion. Recursion is a technique in which a function simply calls itself repeatedly until a condition has been met. The three rules of recursion applies when using recursion in this post:.
Sidebars are indeed essential to a web page, even if the level of its level of attention does not come first. This is because they can help users navigate in different ways, such as content that they may be interested in as opposed to a logical navigational menu. But why would we even want to use recursion for sidebars? What difference does it make as opposed to writing out your sidebar items manually? If you've browsed through the internet for awhile, you might have come accross a website's sidebar and realized that some sidebar items have subsections.
Some sites have sidebars that hide or render certain items based on the page route the user navigated to.
That is powerful! For example, if we look at the image below inside the red circle, the Editors part is an item of the sidebar, and the 3 items following immediately below Code EditorMarkdownText Editor are the subsections:.
You will see by the end of this post that this seemingly complicated sidebar is actually under 50 lines of code! Here is a basic example of how you can extend the sidebar component from this post to be a little more stylish while still retaining the clean feel of it:.
In this tutorial we are going to quickly generate a react project with create-react-app. If you want to get a copy of the repository from github, click here. Go ahead and create a project using the command below. App will be importing and using our Sidebar component by creating Sidebar. Now i'm going to install a CSS library, but you can actually achieve the same working functionality of the sidebar that we will be building without it.
The reason I'm doing this is because I like seeing the additional ripple effects in addition to having icons readily available to use :. Once that is installed, we need to think of a base structure in the user interface that our sidebar will be built upon.
Lets start off hardcoding a couple of items in the sidebar to visualize how this might look like to boost our confidence. Sometimes a little extra confidence can help improve our productivity:. Now that we have boosted our confidence, let's go ahead and define props. With that said, we're also going to expect an items prop that is an array of objects representing each item in the sidebar menu.
We want to keep the functionality as simple as possible or else we could quickly overcomplicate the component.