ngx-translate

BundleTranslations.ts

const languages = ['en', 'fr'];
this.translateService.addLangs(languages);

for (const lang of languages) {
    this.translateService.setTranslation(lang, require('../assets/i18n/' + lang + '.json'));
}

// Set this after 'setTranslation' to avoid unnecessary XHR request
this.translateService.setDefaultLang('en');

const browserLang = this.translateService.getBrowserLang();
this.translateService.use(languages.includes(browserLang) ? browserLang : 'en');

PruningTranslationLoader.ts

import {TranslateLoader} from '@ngx-translate/core';
import {HttpClient} from "@angular/common/http";
import 'rxjs/add/operator/map';

// Translation loader that skips enpty translations so that the key is displayed instead !
// Based on the HTTP loader implementation.
export class PruningTranslationLoader implements TranslateLoader {
    constructor(private http: HttpClient, private prefix: string = '/assets/i18n/', private suffix: string = '.json') {
    }

    public getTranslation(lang: string): any {
        return this.http.get(`${this.prefix}${lang}${this.suffix}`)
            .map((res: Object) => this.process(res));
    }

    private process(object: any) {
        const newObject = {};

        for (const key in object) {
            if (object.hasOwnProperty(key)) {
                if (typeof object[key] === 'object') {
                    newObject[key] = this.process(object[key]);
                }
                else if ((typeof object[key] === 'string') && (object[key] === '')) {
                    // do not copy empty strings
                }
                else {
                    newObject[key] = object[key];
                }
            }
        }

        return newObject;
    }
}