Fetch dictionary data using a custom REST data fetcher

The RestDictionaryServiceConfig type accepts a dataFetcher property. You can use this property to pass a custom data fetcher to your instance of the Dictionary Service. By default, the JSS REST Dictionary service uses the [NativeDataFetcher](https://github.com/Sitecore/jss/blob/dev/packages/sitecore-jss/src/native-fetcher.ts).

To use a REST dictionary service with a custom data fetcher:

1. In a dictionary-service.ts file, create an instance of the RestDictionaryService class and provide the configuration object:

   • For JSS version 22.4 or later, use NativeDataFetcher:

     import {
       NativeDataFetcher,
       NativeDataFetcherResponse,
       RestDictionaryService,
       DictionaryServiceData
     } from '@sitecore-jss/sitecore-jss';
     import config from './config';
     // define your custom data fetcher
     function dataFetcher(url: string, data?: RequestInit): Promise<NativeDataFetcherResponse<DictionaryServiceData>> {
       return new NativeDataFetcher().fetch(url, data);
     }
     export const dictionaryService = new RestDictionaryService({
       apiHost: config.sitecoreApiHost,
       apiKey: config.sitecoreApiKey,
       siteName: config.jssAppName,
       // provide your custom data fetcher to the service instance
       dataFetcher
     });

   • For JSS version 22.3 or earlier, use AxiosDataFetcher:

     import { AxiosResponse } from 'axios';
     import {
       AxiosDataFetcher,
       RestDictionaryService,
       DictionaryServiceData
     } from '@sitecore-jss/sitecore-jss';
     import config from './config';
     
     // define your custom data fetcher
     function dataFetcher(url: string, data?: unknown): Promise<AxiosResponse<DictionaryServiceData>> {
       return new AxiosDataFetcher().fetch(url, data);
     }
     
     export const dictionaryService = new RestDictionaryService({
       apiHost: config.sitecoreApiHost,
       apiKey: config.sitecoreApiKey,
       siteName: config.jssAppName,
       // provide your custom data fetcher to the service instance
       dataFetcher
     });

2. Import and use the new dictionary service:

   import { dictionaryService } from './dictionary-service';
   
   const language = 'en';
   
   dictionaryService.fetchDictionaryData(language).then(data => {
        // do something with the data
   });