React Internationalization Interview Questions 2026

📖 Introduction

This comprehensive guide focuses on React Internationalization interview questions covering i18n and localization. Whether you're preparing for your first React.js interview or looking to refresh your knowledge, this resource provides detailed answers with code examples to help you succeed.

What you'll learn:

React Intl: Using FormatJS for internationalization
Localization: Supporting multiple languages in React apps
Date & Number Formatting: Locale-specific formatting
Translation Management: Managing translation files
Pluralization: Handling plural forms correctly
Best Practices: i18n patterns and implementation strategies

Perfect for:

Developers preparing for React.js interviews focusing on i18n
Frontend engineers building global applications
Teams conducting React technical assessments
Anyone learning React internationalization and seeking comprehensive interview preparation

Keywords: React Internationalization interview questions, React JS interview questions, React.js interview questions, interview questions on react js Key Features:

7+ React Internationalization interview questions with detailed explanations
Code examples for every concept
Updated for 2026 with latest React features
Covers all difficulty levels from beginner to advanced
Practical answers you can use in real interviews

React Internationalization

What is React Intl?
The React Intl library makes internationalization in React straightforward, with off-the-shelf components and an API that can handle everything from formatting strings, dates, and numbers, to pluralization. React Intl is part of FormatJS which provides bindings to React via its components and API.

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What are the main features of React Intl?
Below are the main features of React Intl,
1. Display numbers with separators.
2. Display dates and times correctly.
3. Display dates relative to "now".
4. Pluralize labels in strings.
5. Support for 150+ languages.
6. Runs in the browser and Node.
7. Built on standards.

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What are the two ways of formatting in React Intl?

The library provides two ways to format strings, numbers, and dates:

Using react components:

<FormattedMessage
  id={"account"}
  defaultMessage={"The amount is less than minimum balance."}
/>

Using an API:

const messages = defineMessages({
  accountMessage: {
    id: "account",
    defaultMessage: "The amount is less than minimum balance.",
  },
})

formatMessage(messages.accountMessage)

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How to use <FormattedMessage> as placeholder using React Intl?
The <Formatted... /> components from react-intl return elements, not plain text, so they can't be used for placeholders, alt text, etc. In that case, you should use lower level API formatMessage(). You can inject the intl object into your component using injectIntl() higher-order component and then format the message using formatMessage() available on that object.
```
import React from "react"
import { injectIntl, intlShape } from "react-intl"

const MyComponent = ({ intl }) => {
  const placeholder = intl.formatMessage({ id: "messageId" })
  return <input placeholder={placeholder} />
}

MyComponent.propTypes = {
  intl: intlShape.isRequired,
}

export default injectIntl(MyComponent)
```

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How to access current locale with React Intl?

You can get the current locale in any component of your application using injectIntl():

import { injectIntl, intlShape } from "react-intl"

const MyComponent = ({ intl }) => <div>{`The current locale is ${intl.locale}`}</div>

MyComponent.propTypes = {
  intl: intlShape.isRequired,
}

export default injectIntl(MyComponent)

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How to format date using React Intl?

The injectIntl() higher-order component will give you access to the formatDate() method via the props in your component. The method is used internally by instances of FormattedDate and it returns the string representation of the formatted date.

import { injectIntl, intlShape } from "react-intl"

const stringDate = this.props.intl.formatDate(date, {
  year: "numeric",
  month: "numeric",
  day: "numeric",
})

const MyComponent = ({ intl }) => <div>{`The formatted date is ${stringDate}`}</div>

MyComponent.propTypes = {
  intl: intlShape.isRequired,
}

export default injectIntl(MyComponent)

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How do you localize React applications?
Localization typically involves libraries like react-i18next or react-intl. Set up translation files for different languages and configure the library within your app using provided hooks or components.
```
// Example using react-i18next
import { useTranslation } from "react-i18next"

const MyComponent = () => {
  const { t } = useTranslation()
  return <p>{t("welcome_message")}</p>
}
```
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