Internationalization with @wordpress/i18n

Internationalization (i18n) enables you to prepare your WordPress Block Editor code for translation into multiple languages. The @wordpress/i18n package provides JavaScript utilities that mirror WordPress’s PHP internationalization functions.

Installation

Install the i18n package:

npm install @wordpress/i18n --save

Core Translation Functions

Basic Translation: __()

The __() function retrieves translated text:

import { __ } from '@wordpress/i18n';

const greeting = __( 'Hello World', 'text-domain' );

Contextual Translation: _x()

Use _x() when the same string needs different translations based on context:

import { _x } from '@wordpress/i18n';

// "Post" as a noun
const postNoun = _x( 'Post', 'noun', 'my-plugin' );

// "Post" as a verb
const postVerb = _x( 'Post', 'verb', 'my-plugin' );

UI Context
Content Context

import { _x } from '@wordpress/i18n';

// Button label
const submitLabel = _x( 'Submit', 'button label', 'my-plugin' );

// Form field label  
const submitField = _x( 'Submit', 'form field', 'my-plugin' );

// "Read" as in "read a book"
const readVerb = _x( 'Read', 'past tense of read', 'my-plugin' );

// "Read" as in "he read the book"
const readPast = _x( 'Read', 'present tense', 'my-plugin' );

Plural Forms: _n()

Handle singular and plural forms correctly:

import { _n, sprintf } from '@wordpress/i18n';

function ItemCount( { count } ) {
  const message = sprintf(
    _n( '%d item', '%d items', count, 'my-plugin' ),
    count
  );

  return <p>{ message }</p>;
}

// Usage:
// count = 1: "1 item"
// count = 5: "5 items"

Plural Forms with Context: _nx()

Combine pluralization with context:

import { _nx, sprintf } from '@wordpress/i18n';

function CommentCount( { count } ) {
  const message = sprintf(
    _nx(
      '%d comment',
      '%d comments',
      count,
      'number of comments',
      'my-plugin'
    ),
    count
  );

  return <span>{ message }</span>;
}

String Formatting with sprintf()

The sprintf() function formats strings with placeholders:

import { sprintf, __ } from '@wordpress/i18n';

const userName = 'John';
const greeting = sprintf(
  __( 'Hello, %s!', 'my-plugin' ),
  userName
);
// Result: "Hello, John!"

Format Specifiers:

%s - String
%d - Integer
%f - Float
%1$s, %2$d - Positional arguments (recommended for translations)

Block Registration Example

Translate block metadata and content:

import { registerBlockType } from '@wordpress/blocks';
import { __ } from '@wordpress/i18n';
import { useBlockProps, RichText } from '@wordpress/block-editor';

registerBlockType( 'my-plugin/custom-block', {
  title: __( 'Custom Block', 'my-plugin' ),
  description: __( 'A custom block for displaying content.', 'my-plugin' ),
  category: 'common',
  attributes: {
    content: {
      type: 'string',
      default: '',
    },
  },
  edit: ( { attributes, setAttributes } ) => {
    const blockProps = useBlockProps();

    return (
      <div { ...blockProps }>
        <RichText
          tagName="p"
          value={ attributes.content }
          onChange={ ( content ) => setAttributes( { content } ) }
          placeholder={ __( 'Enter your content here...', 'my-plugin' ) }
        />
      </div>
    );
  },
  save: ( { attributes } ) => {
    const blockProps = useBlockProps.save();
    return (
      <div { ...blockProps }>
        <RichText.Content tagName="p" value={ attributes.content } />
      </div>
    );
  },
} );

Inspector Controls Example

Translate panel labels and help text:

import { InspectorControls } from '@wordpress/block-editor';
import { PanelBody, ToggleControl, TextControl } from '@wordpress/components';
import { __ } from '@wordpress/i18n';

function BlockEdit( { attributes, setAttributes } ) {
  return (
    <>
      <InspectorControls>
        <PanelBody title={ __( 'Block Settings', 'my-plugin' ) } initialOpen={ true }>
          <ToggleControl
            label={ __( 'Enable Feature', 'my-plugin' ) }
            help={ __( 'Toggle this to enable the special feature.', 'my-plugin' ) }
            checked={ attributes.featureEnabled }
            onChange={ ( value ) => setAttributes( { featureEnabled: value } ) }
          />
          <TextControl
            label={ __( 'Custom Label', 'my-plugin' ) }
            help={ __( 'Enter a custom label for this block.', 'my-plugin' ) }
            value={ attributes.customLabel }
            onChange={ ( value ) => setAttributes( { customLabel: value } ) }
          />
        </PanelBody>
      </InspectorControls>
      {/* Block content */}
    </>
  );
}

Dynamic Content Example

Combine translations with dynamic values:

import { __, sprintf } from '@wordpress/i18n';
import { useSelect } from '@wordpress/data';
import { store as coreDataStore } from '@wordpress/core-data';

function PostCount() {
  const { totalPosts, isResolving } = useSelect( ( select ) => {
    const query = { status: 'publish', per_page: 1 };
    const posts = select( coreDataStore ).getEntityRecords( 'postType', 'post', query );
    
    return {
      totalPosts: posts?.length || 0,
      isResolving: select( coreDataStore ).isResolving(
        'getEntityRecords',
        [ 'postType', 'post', query ]
      ),
    };
  }, [] );

  if ( isResolving ) {
    return <p>{ __( 'Loading...', 'my-plugin' ) }</p>;
  }

  return (
    <p>
      { sprintf(
        __( 'You have %d published posts.', 'my-plugin' ),
        totalPosts
      ) }
    </p>
  );
}

RTL (Right-to-Left) Support

Check if the current locale uses RTL:

import { isRTL } from '@wordpress/i18n';

function DirectionalComponent() {
  const alignment = isRTL() ? 'right' : 'left';

  return (
    <div style={ { textAlign: alignment } }>
      { __( 'This text respects text direction', 'my-plugin' ) }
    </div>
  );
}

Managing Locale Data

Setting Locale Data

Load translation data programmatically:

import { setLocaleData } from '@wordpress/i18n';

const translations = {
  '': {
    domain: 'my-plugin',
    lang: 'es_ES',
    plural_forms: 'nplurals=2; plural=(n != 1);',
  },
  'Hello World': [ 'Hola Mundo' ],
};

setLocaleData( translations, 'my-plugin' );

Checking Translations

import { hasTranslation } from '@wordpress/i18n';

if ( hasTranslation( 'Hello World', 'greeting context', 'my-plugin' ) ) {
  console.log( 'Translation exists' );
}

Best Practices

Use Consistent Text Domains

// Good: Consistent domain
const title = __( 'My Plugin', 'my-plugin' );
const subtitle = __( 'Settings', 'my-plugin' );

// Bad: Inconsistent domains
const title = __( 'My Plugin', 'my-plugin' );
const subtitle = __( 'Settings', 'different-domain' );

Avoid String Concatenation

import { sprintf, __ } from '@wordpress/i18n';

const message = sprintf(
  __( 'Welcome back, %s!', 'my-plugin' ),
  userName
);

Provide Context for Translators

// Good: Clear context
const label = _x( 'Post', 'noun: a blog post', 'my-plugin' );

// Better: Even more specific
const buttonText = _x(
  'Save',
  'button label for saving a draft post',
  'my-plugin'
);

Use Positional Arguments

// Good: Positional placeholders allow translators to reorder
const message = sprintf(
  __( '%1$s wrote %2$d posts in %3$s', 'my-plugin' ),
  author,
  postCount,
  month
);

// In some languages, the order might be different:
// "%3$s में %1$s ने %2$d पोस्ट लिखे" (Hindi)

Extract Full Sentences

const message = __(
  'Please check your email for the verification link.',
  'my-plugin'
);

Common Patterns

Loading States

import { __ } from '@wordpress/i18n';
import { Spinner } from '@wordpress/components';

function LoadingComponent( { isLoading } ) {
  if ( isLoading ) {
    return (
      <div>
        <Spinner />
        <p>{ __( 'Loading content...', 'my-plugin' ) }</p>
      </div>
    );
  }

  return <div>{ __( 'Content loaded', 'my-plugin' ) }</div>;
}

Error Messages

import { sprintf, __ } from '@wordpress/i18n';

function ErrorDisplay( { error } ) {
  if ( ! error ) {
    return null;
  }

  return (
    <div className="error-notice">
      <p>
        { sprintf(
          __( 'An error occurred: %s', 'my-plugin' ),
          error.message
        ) }
      </p>
      <button>
        { __( 'Try Again', 'my-plugin' ) }
      </button>
    </div>
  );
}

Conditional Messages

import { __, sprintf } from '@wordpress/i18n';

function StatusMessage( { status, count } ) {
  const messages = {
    draft: sprintf(
      __( 'You have %d draft posts', 'my-plugin' ),
      count
    ),
    published: sprintf(
      __( 'You have %d published posts', 'my-plugin' ),
      count
    ),
    archived: sprintf(
      __( 'You have %d archived posts', 'my-plugin' ),
      count
    ),
  };

  return <p>{ messages[ status ] }</p>;
}

WordPress Script Translations

When enqueueing JavaScript files, set the text domain for automatic translation loading:

<?php
function my_plugin_enqueue_scripts() {
  wp_enqueue_script(
    'my-plugin-script',
    plugins_url( 'build/index.js', __FILE__ ),
    array( 'wp-element', 'wp-i18n' ),
    '1.0.0',
    true
  );

  // Set script translations
  wp_set_script_translations(
    'my-plugin-script',
    'my-plugin',
    plugin_dir_path( __FILE__ ) . 'languages'
  );
}
add_action( 'enqueue_block_editor_assets', 'my_plugin_enqueue_scripts' );

Translation File Generation

Use WP-CLI to extract translatable strings:

# Extract strings from JavaScript files
wp i18n make-pot . languages/my-plugin.pot --domain=my-plugin

# Generate JSON files for JavaScript
wp i18n make-json languages --no-purge

Testing Translations

Test your translations with different locales:

import { setLocaleData, __ } from '@wordpress/i18n';

// Temporarily set test translations
setLocaleData(
  {
    '': { domain: 'my-plugin', lang: 'test' },
    'Hello World': [ 'Test Translation' ],
  },
  'my-plugin'
);

console.log( __( 'Hello World', 'my-plugin' ) );
// Output: "Test Translation"

Common Mistakes to Avoid

Don’t use variables as translatable strings:

// Bad
const key = 'Hello';
const text = __( key, 'my-plugin' );

// Good
const text = __( 'Hello', 'my-plugin' );

Don’t concatenate translations:

// Bad
const msg = __( 'Hello', 'my-plugin' ) + ' ' + __( 'World', 'my-plugin' );

// Good
const msg = __( 'Hello World', 'my-plugin' );

Don’t split sentences:

// Bad
const text = __( 'Click', 'my-plugin' ) + ' ' + __( 'here', 'my-plugin' );

// Good
const text = __( 'Click here', 'my-plugin' );

Next Steps

Learn about Data Management for dynamic content
Explore Filters and Hooks for extending functionality
Read the WordPress i18n documentation
Check the @wordpress/i18n package reference

Overview

Getting Started

Core Concepts

Block Development

Advanced Guides

Internationalization with @wordpress/i18n

Installation

Core Translation Functions

Basic Translation: __()

Contextual Translation: _x()

Plural Forms: _n()

Plural Forms with Context: _nx()

String Formatting with sprintf()

Block Registration Example

Inspector Controls Example

Dynamic Content Example

RTL (Right-to-Left) Support

Managing Locale Data

Setting Locale Data

Checking Translations

Best Practices

Use Consistent Text Domains

Avoid String Concatenation

Provide Context for Translators

Use Positional Arguments

Extract Full Sentences

Common Patterns

Loading States

Error Messages

Conditional Messages

WordPress Script Translations

Translation File Generation

Testing Translations

Common Mistakes to Avoid

Next Steps

Build docs developers (and LLMs) love

Overview

Getting Started

Core Concepts

Block Development

Advanced Guides

Documentation Index

​Installation

​Core Translation Functions

​Basic Translation: __()

​Contextual Translation: _x()

​Plural Forms: _n()

​Plural Forms with Context: _nx()

​String Formatting with sprintf()

​Block Registration Example

​Inspector Controls Example

​Dynamic Content Example

​RTL (Right-to-Left) Support

​Managing Locale Data

​Setting Locale Data

​Checking Translations

​Best Practices

​Use Consistent Text Domains

​Avoid String Concatenation

​Provide Context for Translators

​Use Positional Arguments

​Extract Full Sentences

​Common Patterns

​Loading States

​Error Messages

​Conditional Messages

​WordPress Script Translations

​Translation File Generation

​Testing Translations

​Common Mistakes to Avoid

​Next Steps

Build docs developers (and LLMs) love

Installation

Core Translation Functions

Basic Translation: __()

Contextual Translation: _x()

Plural Forms: _n()

Plural Forms with Context: _nx()

String Formatting with sprintf()

Block Registration Example

Inspector Controls Example

Dynamic Content Example

RTL (Right-to-Left) Support

Managing Locale Data

Setting Locale Data

Checking Translations

Best Practices

Use Consistent Text Domains

Avoid String Concatenation

Provide Context for Translators

Use Positional Arguments

Extract Full Sentences

Common Patterns

Loading States

Error Messages

Conditional Messages

WordPress Script Translations

Translation File Generation

Testing Translations

Common Mistakes to Avoid

Next Steps