Pros of js-lingui

• Framework-agnostic, supporting React, Vue, and vanilla JavaScript
• Supports plural forms and other complex language rules out-of-the-box
• Offers a command-line interface for managing translations

Cons of js-lingui

• Steeper learning curve due to its more complex API
• Less Vue-specific features and integrations

Code Comparison

js-lingui:

import { t } from "@lingui/macro";

function Welcome({ name }) {
  return <h1>{t`Hello ${name}`}</h1>;
}

vue-i18n:

<template>
  <h1>{{ $t('hello', { name: name }) }}</h1>
</template>

<script>
export default {
  props: ['name']
}
</script>

Key Differences

• vue-i18n is specifically designed for Vue.js, while js-lingui is more versatile
• js-lingui uses macros for translation, while vue-i18n relies on template syntax
• vue-i18n has tighter integration with Vue's reactivity system

Use Cases

• Choose vue-i18n for Vue-specific projects with simpler internationalization needs
• Opt for js-lingui in multi-framework environments or when dealing with complex language rules

Community and Ecosystem

• vue-i18n has a larger community within the Vue ecosystem
• js-lingui offers broader support across different JavaScript frameworks

Pros of formatjs

• Framework-agnostic, supporting React, Angular, Vue, and vanilla JavaScript
• More comprehensive internationalization features, including pluralization and gender-aware formatting
• Larger ecosystem with additional tools for message extraction and compilation

Cons of formatjs

• Steeper learning curve due to more complex API and features
• Potentially larger bundle size when using all features
• Less Vue-specific optimizations and integrations

Code Comparison

vue-i18n:

const i18n = new VueI18n({
  locale: 'en',
  messages: {
    en: { hello: 'Hello' },
    ja: { hello: 'こんにちは' }
  }
})

formatjs:

import { IntlProvider, FormattedMessage } from 'react-intl';

const messages = {
  en: { hello: 'Hello' },
  ja: { hello: 'こんにちは' }
};

<IntlProvider messages={messages[locale]} locale={locale}>
  <FormattedMessage id="hello" />
</IntlProvider>

Both libraries provide similar basic functionality for internationalization, but formatjs offers a more comprehensive set of features at the cost of increased complexity. vue-i18n is more tightly integrated with Vue.js, making it easier to use in Vue projects, while formatjs provides a more flexible solution for various frameworks and vanilla JavaScript applications.

Pros of i18next

• Framework-agnostic, can be used with any JavaScript project
• More extensive features, including pluralization and context-based translations
• Larger ecosystem with numerous plugins and integrations

Cons of i18next

• Steeper learning curve due to more complex API
• Requires additional setup for framework-specific integrations

Code Comparison

vue-i18n:

const i18n = new VueI18n({
  locale: 'en',
  messages: {
    en: { hello: 'Hello' },
    ja: { hello: 'こんにちは' }
  }
})

i18next:

i18next.init({
  lng: 'en',
  resources: {
    en: { translation: { hello: 'Hello' } },
    ja: { translation: { hello: 'こんにちは' } }
  }
})

Key Differences

• vue-i18n is specifically designed for Vue.js applications, while i18next is framework-agnostic
• i18next offers more advanced features like pluralization and context-based translations out of the box
• vue-i18n has a simpler API and easier integration with Vue.js components
• i18next has a larger ecosystem with more plugins and integrations available

Both libraries are popular choices for internationalization, with vue-i18n being the go-to option for Vue.js projects and i18next offering more flexibility for various JavaScript environments.

Pros of i18n-ally

• IDE integration: Provides a Visual Studio Code extension for managing translations
• Multi-framework support: Works with various frameworks and libraries, not limited to Vue.js
• Advanced features: Offers machine translation, auto-completion, and inline annotations

Cons of i18n-ally

• Learning curve: May require more setup and configuration compared to vue-i18n
• Dependency: Relies on Visual Studio Code, limiting its use in other development environments

Code Comparison

vue-i18n:

import Vue from 'vue'
import VueI18n from 'vue-i18n'

Vue.use(VueI18n)

const i18n = new VueI18n({
  locale: 'en',
  messages: {
    en: { hello: 'Hello' },
    ja: { hello: 'こんにちは' }
  }
})

i18n-ally (configuration in VS Code settings.json):

{
  "i18n-ally.localesPaths": ["locales"],
  "i18n-ally.keystyle": "nested",
  "i18n-ally.sourceLanguage": "en",
  "i18n-ally.displayLanguage": "en"
}

While vue-i18n is specifically designed for Vue.js applications and offers seamless integration, i18n-ally provides a more versatile solution for managing translations across different frameworks and file formats. i18n-ally's IDE integration offers powerful features for developers, but it may require more initial setup and is primarily focused on Visual Studio Code users.

Pros of Polyglot.js

• Framework-agnostic, can be used with any JavaScript project
• Lightweight and has minimal dependencies
• Supports pluralization and interpolation out of the box

Cons of Polyglot.js

• Lacks built-in integration with Vue.js components and reactivity
• Does not support nested translation keys or locale messages
• Limited features compared to Vue I18n's rich ecosystem

Code Comparison

Vue I18n:

const i18n = new VueI18n({
  locale: 'en',
  messages: {
    en: { greeting: 'Hello, {name}!' },
    fr: { greeting: 'Bonjour, {name}!' }
  }
})

// Usage in a Vue component
this.$t('greeting', { name: 'John' })

Polyglot.js:

const polyglot = new Polyglot();
polyglot.extend({
  en: { greeting: 'Hello, %{name}!' },
  fr: { greeting: 'Bonjour, %{name}!' }
});

// Usage
polyglot.t('greeting', { name: 'John' })

Both libraries offer similar basic functionality for internationalization, but Vue I18n provides deeper integration with Vue.js and more advanced features for complex applications. Polyglot.js is more suitable for simpler projects or when framework independence is required.