Lenora  Hauck

Lenora Hauck

1604993012

Use Constructor in React Functional Component with Custom Hooks

But what is a Constructor?

In class-based_object-oriented programming, a constructor (abbreviation: ctor) is a special type of subroutine called to create an object. It prepares the new object for use, often accepting arguments that the constructor uses to set required member variables. ~ wiki link

So, in simple words with a Constructor we initialize the state of our component, and someone could say that “Function components don’t need a constructor. You can initialise the state in the useState call.”

The problem here is that Function components are… functions. They run whenever you call them. Just like that. This means that we don’t have life-cycles, which also means that we don’t have a place in which we can actually initialize our component with a code that runs only once before the component is rendered for the first time.

A real life example of the problem.

In the following example, we have a modal with an inner form. The performance field has a validation that is in sync with the discipline. Since this form is for editing and creating, we need to know with what validation we want to initialize the form. To achieve it, we pass the validation from the parent to the component via props and handle the validation with a Hook

Image for post

What we also want is to set the field values only when the component is initialised.

Image for post

We have the problem that each time we call the onFocusPerformance() the state is changing due to setPerformanceValidation() which leads to rerun the code block inside the red box and reset the values in the form again._

#react #react-hook #programming #javascript #developer

What is GEEK

Buddha Community

Use Constructor in React Functional Component with Custom Hooks
Autumn  Blick

Autumn Blick

1598839687

How native is React Native? | React Native vs Native App Development

If you are undertaking a mobile app development for your start-up or enterprise, you are likely wondering whether to use React Native. As a popular development framework, React Native helps you to develop near-native mobile apps. However, you are probably also wondering how close you can get to a native app by using React Native. How native is React Native?

In the article, we discuss the similarities between native mobile development and development using React Native. We also touch upon where they differ and how to bridge the gaps. Read on.

A brief introduction to React Native

Let’s briefly set the context first. We will briefly touch upon what React Native is and how it differs from earlier hybrid frameworks.

React Native is a popular JavaScript framework that Facebook has created. You can use this open-source framework to code natively rendering Android and iOS mobile apps. You can use it to develop web apps too.

Facebook has developed React Native based on React, its JavaScript library. The first release of React Native came in March 2015. At the time of writing this article, the latest stable release of React Native is 0.62.0, and it was released in March 2020.

Although relatively new, React Native has acquired a high degree of popularity. The “Stack Overflow Developer Survey 2019” report identifies it as the 8th most loved framework. Facebook, Walmart, and Bloomberg are some of the top companies that use React Native.

The popularity of React Native comes from its advantages. Some of its advantages are as follows:

  • Performance: It delivers optimal performance.
  • Cross-platform development: You can develop both Android and iOS apps with it. The reuse of code expedites development and reduces costs.
  • UI design: React Native enables you to design simple and responsive UI for your mobile app.
  • 3rd party plugins: This framework supports 3rd party plugins.
  • Developer community: A vibrant community of developers support React Native.

Why React Native is fundamentally different from earlier hybrid frameworks

Are you wondering whether React Native is just another of those hybrid frameworks like Ionic or Cordova? It’s not! React Native is fundamentally different from these earlier hybrid frameworks.

React Native is very close to native. Consider the following aspects as described on the React Native website:

  • Access to many native platforms features: The primitives of React Native render to native platform UI. This means that your React Native app will use many native platform APIs as native apps would do.
  • Near-native user experience: React Native provides several native components, and these are platform agnostic.
  • The ease of accessing native APIs: React Native uses a declarative UI paradigm. This enables React Native to interact easily with native platform APIs since React Native wraps existing native code.

Due to these factors, React Native offers many more advantages compared to those earlier hybrid frameworks. We now review them.

#android app #frontend #ios app #mobile app development #benefits of react native #is react native good for mobile app development #native vs #pros and cons of react native #react mobile development #react native development #react native experience #react native framework #react native ios vs android #react native pros and cons #react native vs android #react native vs native #react native vs native performance #react vs native #why react native #why use react native

What are hooks in React JS? - INFO AT ONE

In this article, you will learn what are hooks in React JS? and when to use react hooks? React JS is developed by Facebook in the year 2013. There are many students and the new developers who have confusion between react and hooks in react. Well, it is not different, react is a programming language and hooks is a function which is used in react programming language.
Read More:- https://infoatone.com/what-are-hooks-in-react-js/

#react #hooks in react #react hooks example #react js projects for beginners #what are hooks in react js? #when to use react hooks

Lenora  Hauck

Lenora Hauck

1604993012

Use Constructor in React Functional Component with Custom Hooks

But what is a Constructor?

In class-based_object-oriented programming, a constructor (abbreviation: ctor) is a special type of subroutine called to create an object. It prepares the new object for use, often accepting arguments that the constructor uses to set required member variables. ~ wiki link

So, in simple words with a Constructor we initialize the state of our component, and someone could say that “Function components don’t need a constructor. You can initialise the state in the useState call.”

The problem here is that Function components are… functions. They run whenever you call them. Just like that. This means that we don’t have life-cycles, which also means that we don’t have a place in which we can actually initialize our component with a code that runs only once before the component is rendered for the first time.

A real life example of the problem.

In the following example, we have a modal with an inner form. The performance field has a validation that is in sync with the discipline. Since this form is for editing and creating, we need to know with what validation we want to initialize the form. To achieve it, we pass the validation from the parent to the component via props and handle the validation with a Hook

Image for post

What we also want is to set the field values only when the component is initialised.

Image for post

We have the problem that each time we call the onFocusPerformance() the state is changing due to setPerformanceValidation() which leads to rerun the code block inside the red box and reset the values in the form again._

#react #react-hook #programming #javascript #developer

Mark Mara

Mark Mara

1607399166

Class-less Components in React

While coding this week, I had to convert one of my class components in React to a functional component.

Why would I need to do that? After all, the parent component sees the two types of components as identical. Sure, functional components can be shorter, require less boilerplate, and maybe even perform better. But that’s not why I needed to do it. I was using an npm package that had React hooks and hooks are for functional components only. React Hooks, added in React 16.8, allow functional components to manage state and replace lifecycle methods. To use the hook I needed I had to convert my class components to a functional.

Here are the steps I followed to change my class component to a functional component:

#react-hook-useeffect #useeffect #react-hook #react-hook-usestate #react

How to Fix Memory Leaks with a Simple React Custom Hook

See error logs in your console with the message “Cannot perform state update on an unmounted component” from your React application? There is a simple cause and easy fix.

The Cause

React components which run asynchronous operations and perform state updates can cause memory leaks if state updates are made after the component is unmounted. Here is a common scenario where this could pop up:

  1. User performs an action triggering an event handler to fetch data from an API.
  2. The user clicks on a link, navigating them to a different page, before (1) completes.
  3. The event handler from (1) completes the fetch, and calls a state setter function, passing it the data that was retrieved from the API.

Since the component was unmounted, a state setter function is being called in a component that is no longer mounted. Essentially, the setter function is updating state no longer exists. Memory Leak.

Here is a contrived example of unsafe code:

const [value, setValue] = useState({});
useEffect(() => {
    const runAsyncOperation = () => {
        setTimeout(() => {
            // MEMORY LEAK HERE, COMPONENT UNMOUNTED
            setValue({ key: 'value' });
        }, 1000);
    }
    runAsyncOperation();
    // USER NAVIGATES AWAY FROM PAGE HERE,
    // IN LESS THAN 1000 MS
}, []); 

#web-development #react #javascript #react-hook #custom-react-hook