# Introduction
[](https://travis-ci.org/i18next/i18next-xhr-backend)
[](https://coveralls.io/github/i18next/i18next-xhr-backend)
[](https://www.npmjs.com/package/i18next-xhr-backend)
[]()
[](https://david-dm.org/i18next/i18next-xhr-backend)
This is a simple i18next backend to be used in the browser. It will load resources from a backend server using the xhr API.
# Getting started
Source can be loaded via [npm](https://www.npmjs.com/package/i18next-xhr-backend), bower or [downloaded](https://github.com/i18next/i18next-xhr-backend/blob/master/i18nextXHRBackend.min.js) from this repo.
```
# npm package
$ npm install i18next-xhr-backend
# bower
$ bower install i18next-xhr-backend
```
Wiring up:
```js
import i18next from 'i18next';
import XHR from 'i18next-xhr-backend';
i18next.use(XHR).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.i18nextXHRBackend`
## Backend Options
```js
{
// path where resources get loaded from, or a function
// returning a path:
// function(lngs, namespaces) { return customPath; }
// the returned path will interpolate lng, ns if provided like giving a static path
loadPath: '/locales/{{lng}}/{{ns}}.json',
// path to post missing resources
addPath: 'locales/add/{{lng}}/{{ns}}',
// your backend server supports multiloading
// /locales/resources.json?lng=de+en&ns=ns1+ns2
// Adapter is needed to enable MultiLoading https://github.com/i18next/i18next-multiload-backend-adapter
// Returned JSON structure in this case is
// {
// lang : {
// namespaceA: {},
// namespaceB: {},
// ...etc
// }
// }
allowMultiLoading: false, // set loadPath: '/locales/resources.json?lng={{lng}}&ns={{ns}}' to adapt to multiLoading
// parse data after it has been fetched
// in example use https://www.npmjs.com/package/json5
// here it removes the letter a from the json (bad idea)
parse: function(data) { return data.replace(/a/g, ''); },
//parse data before it has been sent by addPath
parsePayload: function(namespace, key, fallbackValue) { return { key } },
// allow cross domain requests
crossDomain: false,
// allow credentials on cross domain requests
withCredentials: false,
// overrideMimeType sets request.overrideMimeType("application/json")
overrideMimeType: false,
// custom request headers sets request.setRequestHeader(key, value)
customHeaders: {
authorization: 'foo',
// ...
},
// define a custom xhr function
// can be used to support XDomainRequest in IE 8 and 9
//
// 'url' will be passed the value of 'loadPath'
// 'options' will be this entire options object
// 'callback' is a function that takes two parameters, 'data' and 'xhr'.
// 'data' should be the key:value translation pairs for the
// requested language and namespace, or null in case of an error.
// 'xhr' should be a status object, e.g. { status: 200 }
// 'data' will be a key:value object used when saving missing translations
ajax: function (url, options, callback, data) {},
// adds parameters to resource URL. 'example.com' -> 'example.com?v=1.3.5'
queryStringParams: { v: '1.3.5' }
}
```
Options can be passed in:
**preferred** - by setting options.backend in i18next.init:
```js
import i18next from 'i18next';
import XHR from 'i18next-xhr-backend';
i18next.use(XHR).init({
backend: options,
});
```
on construction:
```js
import XHR from 'i18next-xhr-backend';
const xhr = new XHR(null, options);
```
via calling init:
```js
import XHR from 'i18next-xhr-backend';
const xhr = new XHR();
xhr.init(null, options);
```
## Misc
#### TypeScript definitions
- Install from `@types` (for TypeScript v2 and later):
npm install --save-dev @types/i18next-xhr-backend
- Install from `typings`:
typings install --save --global dt~i18next-xhr-backend
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