伊藤 直子

伊藤 直子

1661242080

React で状態配列から要素を削除する方法

配列 filter() メソッド

React で状態配列から要素を削除するには、配列でfilter()メソッドを呼び出し、削除する要素を除く配列内trueのすべての要素の条件を指定してから、を使用setStateして状態を次の結果で更新します。filter().

import { useState } from 'react';

export default function App() {
  const initialState = [
    { id: 1, name: 'Banana', amount: 5 },
    { id: 2, name: 'Apple', amount: 6 },
  ];

  const removeSecond = () => {
    setFruits((current) =>
      current.filter((fruit) => fruit.id !== 2)
    );
  };

  const [fruits, setFruits] = useState(initialState);

  return (
    <div style={{ margin: '16px' }}>
      <button onClick={removeSecond}>Remove second</button>
      {fruits.map((fruit) => (
        <div key={fruit.id}>
          <h2>Name: {fruit.name}</h2>
          <h2>Amount: {fruit.amount}</h2>
          <hr />
        </div>
      ))}
    </div>
  );
}

React の状態配列からオブジェクトを削除します。

2の を持たない配列内の要素のみに対する条件をコールバックid 2から返すことにより、 を含むフルーツ オブジェクトを削除します。これを行うと、 から返される配列からターゲット要素が除外されます。filter()trueidfilter()

const initialState = [
  { id: 1, name: 'Banana', amount: 5 },
  { id: 2, name: 'Apple', amount: 6 },
];

const secondRemoved = initialState.filter((fruit) => fruit.id !== 2);

// [ { id: 1, name: 'Banana', amount: 5 } ]
console.log(secondRemoved);

これAppは機能的なコンポーネントなので、useState()React フックを使用して初期状態の配列を作成します。返される最初の値useState()により、状態データにアクセスできます。2 番目の値は、状態を更新するために使用される関数です (一般に と呼ばれsetStateます)。現在/最新の状態を確実に取得するために、setState(ここで名前を付けた) に関数を渡します。setFruits

const removeSecond = () => {
  // "current" contains the latest state array
  setFruits((current) =>
    current.filter((fruit) => fruit.id !== 2)
  );
};

ヒントsetState:新しい状態が現在の状態データから計算されるときは、必ず に関数を渡します。

React で状態を直接変更しないでください

次のような関数を使用して直接変更して配列から要素を削除しようとしても機能しsplice()ないことに注意してください。

const removeSecond = () => {
  // Find the index of the element to be removed
  const secondIndex = fruits.findIndex((fruit) => fruit.id === 2);

  // Mutating the array like this will not update the view
  fruits.splice(secondIndex, 1);
};

State は React では不変であることを意図しているため、配列を変更して更新することはできません。filter()ビューを更新するには、から返された新しい配列に置き換える必要があります。

複数の条件に基づく状態配列からの要素の削除

複数の条件に基づいて状態配列から要素を削除する必要がある場合は、論理 AND (&&)または論理 OR (&&)演算子を使用できます。

論理 OR (||) 演算子の使用

||論理 OR ( ) 演算子を使用して状態配列から要素を削除する例を次に示します。

const initialState = [
  { id: 1, name: 'Banana', amount: 5 },
  { id: 2, name: 'Apple', amount: 6 },
  { id: 3, name: 'Orange', amount: 10 },
  { id: 4, name: 'Watermelon', amount: 1 },
];

const [fruits, setFruits] = useState(initialState);

const remove = () => {
  setFruits((current) =>
    current.filter(
      (fruit) =>
        fruit.name === 'Orange' || fruit.name === 'Apple'
    )
  );
};

||オペランドのセットを演算子と組み合わせると、オペランドのtrue 少なくとも 1 つが に評価される場合になりますtrue。メソッドでこの演算子を使用することにより、またはと等しいfilter()フルーツ オブジェクトのみを含む新しい配列を返します。name'Orange''Apple'

論理積 (&&) 演算子の使用

&&論理 AND ( ) 演算子を使用して状態配列から要素を削除する例を次に示します。

const initialState = [
  { id: 1, name: 'Banana', amount: 5 },
  { id: 2, name: 'Apple', amount: 6 },
  { id: 3, name: 'Orange', amount: 10 },
  { id: 4, name: 'Watermelon', amount: 1 },
];

const [fruits, setFruits] = useState(initialState);

const remove = () => {
  setFruits((current) =>
    current.filter(
      (fruit) => fruit.id !== 2 && fruit.id !== 4
    )
  );
};

オペランドを演算子と組み合わせると、すべてのオペランドが の場合&&にのみ結果が得られます。true true

filter()メソッドを演算子と組み合わせることで、との s を&&持つ果物オブジェクトを削除する複合ブール式を指定できます。id24

ド・モルガンの法則による複合ブール式の単純化

ド・モルガンの法則の1 つを使用して、前の例の AND 条件を OR 条件に変換し、否定の数を減らすことができます。

const remove = () => {
  setFruits((current) =>
    current.filter(
      (fruit) => !(fruit.id === 2 || fruit.id === 4)
    )
  );
};

この変換により、式が読みやすく理解しやすくなります。

ソース: https://codingbeautydev.com/react-remove-element-from-state-array/

#react 

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React で状態配列から要素を削除する方法
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.

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Mathew Rini

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How to Select and Hire the Best React JS and React Native Developers?

Since March 2020 reached 556 million monthly downloads have increased, It shows that React JS has been steadily growing. React.js also provides a desirable amount of pliancy and efficiency for developing innovative solutions with interactive user interfaces. It’s no surprise that an increasing number of businesses are adopting this technology. How do you select and recruit React.js developers who will propel your project forward? How much does a React developer make? We’ll bring you here all the details you need.

What is React.js?

Facebook built and maintains React.js, an open-source JavaScript library for designing development tools. React.js is used to create single-page applications (SPAs) that can be used in conjunction with React Native to develop native cross-platform apps.

React vs React Native

  • React Native is a platform that uses a collection of mobile-specific components provided by the React kit, while React.js is a JavaScript-based library.
  • React.js and React Native have similar syntax and workflows, but their implementation is quite different.
  • React Native is designed to create native mobile apps that are distinct from those created in Objective-C or Java. React, on the other hand, can be used to develop web apps, hybrid and mobile & desktop applications.
  • React Native, in essence, takes the same conceptual UI cornerstones as standard iOS and Android apps and assembles them using React.js syntax to create a rich mobile experience.

What is the Average React Developer Salary?

In the United States, the average React developer salary is $94,205 a year, or $30-$48 per hour, This is one of the highest among JavaScript developers. The starting salary for junior React.js developers is $60,510 per year, rising to $112,480 for senior roles.

* React.js Developer Salary by Country

  • United States- $120,000
  • Canada - $110,000
  • United Kingdom - $71,820
  • The Netherlands $49,095
  • Spain - $35,423.00
  • France - $44,284
  • Ukraine - $28,990
  • India - $9,843
  • Sweden - $55,173
  • Singapore - $43,801

In context of software developer wage rates, the United States continues to lead. In high-tech cities like San Francisco and New York, average React developer salaries will hit $98K and $114per year, overall.

However, the need for React.js and React Native developer is outpacing local labour markets. As a result, many businesses have difficulty locating and recruiting them locally.

It’s no surprise that for US and European companies looking for professional and budget engineers, offshore regions like India are becoming especially interesting. This area has a large number of app development companies, a good rate with quality, and a good pool of React.js front-end developers.

As per Linkedin, the country’s IT industry employs over a million React specialists. Furthermore, for the same or less money than hiring a React.js programmer locally, you may recruit someone with much expertise and a broader technical stack.

How to Hire React.js Developers?

  • Conduct thorough candidate research, including portfolios and areas of expertise.
  • Before you sit down with your interviewing panel, do some homework.
  • Examine the final outcome and hire the ideal candidate.

Why is React.js Popular?

React is a very strong framework. React.js makes use of a powerful synchronization method known as Virtual DOM, which compares the current page architecture to the expected page architecture and updates the appropriate components as long as the user input.

React is scalable. it utilises a single language, For server-client side, and mobile platform.

React is steady.React.js is completely adaptable, which means it seldom, if ever, updates the user interface. This enables legacy projects to be updated to the most new edition of React.js without having to change the codebase or make a few small changes.

React is adaptable. It can be conveniently paired with various state administrators (e.g., Redux, Flux, Alt or Reflux) and can be used to implement a number of architectural patterns.

Is there a market for React.js programmers?
The need for React.js developers is rising at an unparalleled rate. React.js is currently used by over one million websites around the world. React is used by Fortune 400+ businesses and popular companies such as Facebook, Twitter, Glassdoor and Cloudflare.

Final thoughts:

As you’ve seen, locating and Hire React js Developer and Hire React Native developer is a difficult challenge. You will have less challenges selecting the correct fit for your projects if you identify growing offshore locations (e.g. India) and take into consideration the details above.

If you want to make this process easier, You can visit our website for more, or else to write a email, we’ll help you to finding top rated React.js and React Native developers easier and with strives to create this operation

#hire-react-js-developer #hire-react-native-developer #react #react-native #react-js #hire-react-js-programmer

Franz Becker

Franz Becker

1651604400

React Starter Kit: Build Web Apps with React, Relay and GraphQL.

React Starter Kit — "isomorphic" web app boilerplate   

React Starter Kit is an opinionated boilerplate for web development built on top of Node.js, Express, GraphQL and React, containing modern web development tools such as Webpack, Babel and Browsersync. Helping you to stay productive following the best practices. A solid starting point for both professionals and newcomers to the industry.

See getting started guide, demo, docs, roadmap  |  Join #react-starter-kit chat room on Gitter  |  Visit our sponsors:

 

Hiring

Getting Started

Customization

The master branch of React Starter Kit doesn't include a Flux implementation or any other advanced integrations. Nevertheless, we have some integrations available to you in feature branches that you can use either as a reference or merge into your project:

You can see status of most reasonable merge combination as PRs labeled as TRACKING

If you think that any of these features should be on master, or vice versa, some features should removed from the master branch, please let us know. We love your feedback!

Comparison

 

React Starter Kit

React Static Boilerplate

ASP.NET Core Starter Kit

App typeIsomorphic (universal)Single-page applicationSingle-page application
Frontend
LanguageJavaScript (ES2015+, JSX)JavaScript (ES2015+, JSX)JavaScript (ES2015+, JSX)
LibrariesReact, History, Universal RouterReact, History, ReduxReact, History, Redux
RoutesImperative (functional)DeclarativeDeclarative, cross-stack
Backend
LanguageJavaScript (ES2015+, JSX)n/aC#, F#
LibrariesNode.js, Express, Sequelize,
GraphQL		n/aASP.NET Core, EF Core,
ASP.NET Identity
SSRYesn/an/a
Data APIGraphQLn/aWeb API

Backers

♥ React Starter Kit? Help us keep it alive by donating funds to cover project expenses via OpenCollective or Bountysource!

lehneres Tarkan Anlar Morten Olsen Adam David Ernst Zane Hitchcox  

How to Contribute

Anyone and everyone is welcome to contribute to this project. The best way to start is by checking our open issues, submit a new issue or feature request, participate in discussions, upvote or downvote the issues you like or dislike, send pull requests.

Learn More

Related Projects

  • GraphQL Starter Kit — Boilerplate for building data APIs with Node.js, JavaScript (via Babel) and GraphQL
  • Membership Database — SQL schema boilerplate for user accounts, profiles, roles, and auth claims
  • Babel Starter Kit — Boilerplate for authoring JavaScript/React.js libraries

Support

License

Copyright © 2014-present Kriasoft, LLC. This source code is licensed under the MIT license found in the LICENSE.txt file. The documentation to the project is licensed under the CC BY-SA 4.0 license.

Author: kriasoft
Source Code: https://github.com/kriasoft/react-starter-kit
License: MIT License

#graphql #react 

Juned Ghanchi

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React Native App Developers India, React Native App Development Company

Expand your user base by using react-native apps developed by our expert team for various platforms like Android, Android TV, iOS, macOS, tvOS, the Web, Windows, and UWP.

We help businesses to scale up the process and achieve greater performance by providing the best react native app development services. Our skilled and experienced team’s apps have delivered all the expected results for our clients across the world.

To achieve growth for your business, hire react native app developers in India. You can count on us for all the technical services and support.

#react native app development company india #react native app developers india #hire react native developers india #react native app development company #react native app developers #hire react native developers

Abhishek Jaiswal

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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