# Introduction
[](https://travis-ci.org/i18next/i18next-icu)
[](https://coveralls.io/github/i18next/i18next-icu)
[](https://www.npmjs.com/package/i18next-icu)
This changes i18n format from i18next json to ICU using [formatjs/intl-messageformat](https://github.com/formatjs/formatjs/tree/main/packages/intl-messageformat)
## Advice
When using this module, only the ICU message format is respected, this means the i18next format interpolation will not work.
So for example instead of `Hy {{name}}!` it is `Hy {name}!`
# Getting started
Source can be loaded via [npm](https://www.npmjs.com/package/i18next-icu) or [downloaded](https://github.com/i18next/i18next-icu/blob/master/i18nextICU.min.js) from this repo.
```
# npm package
$ npm install i18next-icu
# peer dependencies
$ npm install intl-messageformat
```
Wiring up:
```js
import i18next from "i18next";
import ICU from "i18next-icu";
i18next.use(ICU).init(i18nextOptions);
```
- As with all modules you can either pass the constructor function (class) to the i18next.use or a concrete instance.
- If you don't use a module loader it will be added to `window.i18nextICU`
## Backend Options
```js
{
// per default icu functions are parsed once and cached for subsequent calls
memoize: true,
// memoize if not having a lookup and just using the key fallback as value
memoizeFallback: false,
// which events should clear the cache, can be set to false or string of events separated by " "
bindI18n: '',
// which events on resourceSource should clear the cache, can be set to false or string of events separated by " "
bindI18nStore: '',
// Will be run when parser throws an error. Can return any string, which can be used as a fallback, in case of broken translation.
// If omitted, the default swallows the error and returns the unsubstituted string (res)
parseErrorHandler: (err, key, res, options) => {},
// Transform the language code prior to ICU locale parsing, useful for supporting psuedo-locales like en-ZZ
// If omitted, the default leaves the language code as is
parseLngForICU: (lng) => lng,
// Automatically escape HTML special characters in variable values to prevent ICU parsing issues
// When true, characters like <, >, &, ", ' in variables are escaped to their HTML entities
// This prevents strings like "user:<" from being truncated or causing parsing errors
// Default: false (to maintain backward compatibility)
escapeVariables: false,
}
```
Options can be passed in by setting options.i18nFormat in i18next.init:
```js
import i18next from "i18next";
import ICU from "i18next-icu";
i18next.use(ICU).init({
i18nFormat: options
});
```
### more complete sample
```js
import i18next from "i18next";
import ICU from "i18next-icu";
i18next.use(ICU).init({
lng: "en",
resources: {
en: {
translation: {
key:
"You have {numPhotos, plural, " +
"=0 {no photos.}" +
"=1 {one photo.}" +
"other {# photos.}}"
}
}
}
});
i18next.t("key", { numPhotos: 1000 }); // -> You have 1,000 photos.
```
## hints
Using i18next-icu - non of the i18next specific stuff will be available. You will have to rely on what intl-messageformat provides by calling the `t` function with needed options.
All extra features build around i18next plurals, interpolation, context do not get applied to messageformat based keys.
## Migration guide
### 1.x.x -> 2.0.0
- updated `intl-messageformat` dependency. Adding locales-data is no longer needed.
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