If you are learning React and you get stuck on these kinds of above questions then definitely you are doing mistakes in your learning process. There is no doubt that ReactJS is the most popular library among frontend developers and its popularity is continuously increasing day by day. The website running on ReactJS looks beautiful and most of the beginners in development get attracted to ReactJs (developed by Facebook) as well but a common mistake that a lot of developers and experienced people make is jumping directly into ReactJS (or some other library and framework) without knowing the prerequisites. If you will directly go to the React you will face a lot of problems while learning this library and in interviews as well.
You will get stuck during your interview if you will be asked some questions related to ES6, JSX, Babel, Package manager, basic javascript, or some other fundamental concepts. We are going to discuss some prerequisites and some basic concepts that you should know before you jump to the React. These basic concepts will also help you to pick up some other frameworks and libraries of javascript in the future.
Every front-end developer starts their journey with HTML and CSS. So before you start learning to react you should have a good command of writing HTML and CSS. You should know how to write semantic HTML tags, how to write CSS selectors, how to use classes, how to implement a CSS reset, box model, how to reset to border-box, flexbox, how to write responsive web applications including media queries, and how to build a frontend application using HTML and CSS.
2. JSX (Javascript XML) & Babel
In React you will work with JSX that looks like HTML and you can consider it like HTML-flavored JavaScript. It is the easiest way to add HTML code inside javascript or you can say it is the extension of the Javascript language syntax. You should have a complete understanding of what is JSX before you start learning React. Just take a look at the code below…
const h1 = <h1>Hello Programmers</h1>;
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When you will look at the above code for the first time it might be confusing for you. Is it Javascript? or HTML? or something else? If you will run the above code in HTML file it won’t run but the code contains HTML tag <h1>Hello world</h1>. Basically, JSX extends the ECMAScript so that XML/HTML-like text can co-exist along with JavaScript react code. Understand it from the picture and code given below…
var MyComponent = React.createClass({
render :function () {
return(
<h2>Hello Programmers!</h2>
);
}
});
ReactDOM.render(<MyComponent/>, document.getElementById('content'));
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Another thing you should know about is Babel. Babel is a compiler that transforms HTML-like text found in JavaScript files into standard JavaScript objects. It takes features from the latest version of javascript or ECMAScript 2015 (ES6 ) and brings them down to ES5 or regular javascript. Make sure that your concept needs to be clear about JSX and Babel if you want to go with React. Check how Babel does the conversion from the link here.
3. Fundamentals of Javascript and ES6
No matter what… you can’t get better at React if your javascript fundamental is not clear. During the interviews, it is one of the essential skills to learn before moving to react. Javascript is one of the most confusing languages for developers and it ignores small errors that can create a problem in your project if you won’t notice them earlier. So make sure that you first clear your basic concept about javascript and then you move to the advanced version of ECMAScript5 and ECMAScript6. Some of the topics are given below but make sure that you explore as much as you can and build some projects as well for in-depth knowledge in javascript.
Remember that building the basic foundation of javascript will help you to learn any framework but if the concept won’t be clear you will get stuck in any javascript framework. Also, the interviewer will check your fundamentals in javascript first before moving to the React.
- Start with variables, numbers, boolean, strings and make your concepts clear about other very basic fundamentals. Make some small app on that like a calculator to see how things work together.
- Learn about operators, conditionals, functions, loops, javascript keywords, arrays, objects, and other fundamentals.
- Event handling, DOM manipulation, and how ‘this’ keyword works are totally different in javascript (which is confusing for most of the developers).
- Higher-order function, callback function, arrow function, state (how state and setState() function works) scope, class & constructors, extends and inheritance, map, reduce, filter, promises, modules, closures, const, let (difference between var, let and const) and other features of ES5 and ES6.
4. Package Manager (Node Npm)
When you will be working with ReactJS you’ll have to install many, smaller software packages. Package in javascript contains all the files needed for a module and modules are the javascript libraries that can be included in the Node project. Packages contain two things…package.json files js files. To install these packages you need a good installer that can help you to download and install software packages easily without worrying about the dependencies. Here NPM (Node package manager) plays a role and helps you to install and keep track of javascript software. You can use NodeJs or Yarn to manage these software packages. You can install NPM by installing Node.js. When you install Node.js, NPM will install automatically.
So before moving to React, you should have a solid understanding NPM (Node package manager) registry and how to install packages using NPM. NPM registry keeps track of the file that has been submitted. Anybody can submit these files (packages or modules). In short NPM registry is the place where developers can go and get the software to build software.
Let’s suppose a person has written some javascript file that is really useful. He/she thinks that the other people might use it so he/she pushes it to the NPM registry. Somebody else can get it from the NPM web registry and download it for their own purpose. Learn about the NPM more from CSDTCentre.
5. Git and CLI (Command Line Interface)
Git (version control) is another must-have skill a developer should have to store their project on GitHub, Bitbucket, and GitLab (Code hosting platform). It helps developers to work and collaborate with each other and it allows them to track and host different versions of project files. You should have good knowledge that how Git and these code hosting platforms work. Developers use the command of Git to track the version of your files, so learn how to use all the commands such as push, pull, add, commit, etc. Also learn about merging, branching, handling merging conflicts, etc.
Everything in React you will be doing with the help of CLI (Command-line interface). Installing packages, using NPM, creating a react app, running react application, and a lot of things so you really need to make a habit of using CLI. Below is an example of running a react application using CLI.
