Implementation of i18n with documentation

All files are documented. For further details please read them.

frontend/public/i18n/EN.txt

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+# English translations (some examples to remove)
+
+login.guest.login=log in
+login.guest.register=register
+login.guest.welcome=Please Register here
+login.success=You are now registered as $name 
+
+#=====================================================

frontend/public/i18n/FR.txt

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+# Traductions françaises (Quelques examples a enlever)
+
+login.guest.login=s'identifier
+login.guest.register=s'enregistrer
+login.guest.welcome=Veuillez vous enregistrer ici
+login.success=Vous êtes maintenant identifié comme $name 
+
+#=====================================================

frontend/src/i18n.js

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+/**
+ * Usage:
+ * import i18n from './i18n.js'
+ *
+ * console.log( i18n('parentcontext.childcontext.key', {user: username}) );
+ *
+ * language is loaded from cookie: lang=XX
+ * translations are loaded from /public/i18n/XX.txt
+ *
+ */
+
+const default_lang = "EN";
+let langs;
+
+
+/**
+ * Fetch the translation from a key using the current language.
+ * could also replace certain value of the form `$variable` by providing an object
+ * with { variable: "value" }
+ * @param key :string translation key (can be null)
+ * @param options: Object element to replace in the translation
+ *
+ * @return :string The translated text
+ */
+function i18n(key, options) {
+	let ret = langs[key];
+	if(options != null){
+		for (let key in options) {
+			ret = ret.replaceAll("$" + key, options[key]);
+		}
+	}
+	return ret;
+}
+
+async function reloadLang(){
+	langs = await loadLangs();
+}
+reloadLang();
+
+export default i18n;
+
+
+//
+// Those functions are utility functions use by previous exported functions.
+//
+
+/**
+ * Return the content of a cookie with specified key
+ * @param key cookie name
+ */
+function getCookie(key){
+	key = key + "="
+	let cookies = decodeURIComponent(document.cookie).split(";");
+	for (let el of cookies) {
+		el = el.trimStart();
+		if(el.indexOf(key) == 0){
+			return el.substr(key.length, el.length);
+		}
+	}
+	return "";
+}
+
+/**
+ * Function that load the file with translation from the specified lang and return a dictionnary
+ * @param select the language to load. could be null to fetch the cookies for an answer
+ * if nothing is found. default to EN.txt
+ */
+async function loadLangs(lang){
+	lang = lang != null ? lang : getCookie("lang");
+	lang = lang != "" ? lang : default_lang;
+
+	const filename = "./i18n/" + lang.toUpperCase() + ".txt";
+	const content = await (await fetch(filename)).text();
+	const lines = content.split("\n");
+
+	let filteredLines = {};
+	for (let line of lines) {
+		if(!line.trim().startsWith("#") && line.trim() != ""){
+			let split = line.indexOf("=")
+			filteredLines[line.substr(0, split)] = line.substr(split+1, line.length);
+		};
+	}
+	return filteredLines;
+}