major: i18n concept implementation

src/scripts/intl.js

@@ -0,0 +1,178 @@
+/*
+  js intl, inspired by danabr/jsI18n
+*/
+class JsI18n {
+
+  constructor() {
+    this.locale = ""; //Current locale
+    this.locales = new Array(); //Available locales
+  }
+
+  /*
+    Method for automatically detecting the language, does not work in every browser.
+  */
+  detectLanguage() {
+    if (localStorage.getItem('language') || (window.navigator.language !== null && window.navigator.language !== undefined)) {
+      this.setLocale(localStorage.getItem('language') || window.navigator.language.slice(0, 2));
+    } else {
+      console.error('Language not found');
+      this.setLocale('en');
+    }
+  };
+
+  /*
+    Translates tag contents and
+    attributes depending on the
+    value of key.
+  */
+  translateTag(node, key) {
+    if (key.indexOf("=") == -1) { //Simple key
+      this.translateNodeContent(node, key);
+    } else { //Attribute/key pairs
+      var parts = key.split(";");
+
+      for (var i = 0; i < parts.length; i++) {
+        var pair = parts[i].split("=");
+        var attr = pair[0].toLowerCase().trim();
+        var k = pair[1].trim();
+
+        if (attr == "html") {
+          this.translateNodeContent(node, k);
+        } else {
+          this.translateNodeContent(node.attributes[attr], k);
+        }
+      }
+    }
+  }
+
+  /**
+    Replace the content of the given node
+    if there is a translation for the given key.
+  **/
+  translateNodeContent(node, key) {
+    var translation = this.t(key);
+    if (node != null && translation != undefined) {
+      if (node.nodeType == 1) { //Element
+        try {
+          node.innerHTML = translation;
+        } catch (e) {
+          node.text = translation;
+        }
+      } else if (node.nodeType == 2) { //Attribute
+        node.value = translation;
+      }
+    }
+  }
+
+  /*
+    Helper for translating a node
+    and all its child nodes.
+  */
+  processNode(node) {
+    if (node != undefined) {
+      if (node.nodeType == 1) { //Element node
+
+        var key = node.attributes["data-trans"];
+        if (key != null) {
+          this.translateTag(node, key.nodeValue);
+        }
+      }
+
+      //Process child nodes
+      var children = node.childNodes;
+      for (var i = 0; i < children.length; i++) {
+        this.processNode(children[i]);
+      }
+    }
+  }
+
+  /*
+    Adds a locale to the list,
+    replacing the translations
+    if the locale is already defined.
+  */
+  addLocale(locale, translations) {
+    this.locales[locale.toString()] = translations;
+  }
+
+  /*
+    Sets the locale to use when translating.
+  */
+  setLocale(locale) {
+    try {
+      fetch(`/locales/${locale}.json`).then((result) => {
+        if (result.ok) {
+          result.json().then(e => {
+            this.addLocale(locale, e);
+            this.processPage();
+          });
+        }
+      });
+      this.locale = locale;
+    } catch {
+      if (locale != "en") {
+        console.warn(`Locale not found: ${locale}, fallback to english`);
+        this.setLocale("en");
+      } else {
+        console.error("Language not found");
+      }
+    }
+  }
+
+  /*
+    Fetches the translation associated with the given key.
+  */
+  t(key) {
+    var translations = this.locales[this.locale];
+    if (translations != undefined) {
+      let translation = key.toString().split('.').reduce((o, i) => (o ? o[i] : undefined), translations);
+      if(typeof translation == "string") {
+        return translation;
+      } else {
+        return translations[key.toString()];
+      }
+    }
+    return undefined;
+  }
+
+  /*
+    Alias for JsI18n.t
+  */
+  translate(key) {
+    this.t(key);
+  }
+
+  /**
+    Replaces the contents of all tags
+    that have the data-trans attribute set.
+  **/
+  processPage() {
+    this.processNode(document.getElementsByTagName("html")[0]);
+  }
+}
+
+//Global
+jsI18n = new JsI18n;
+
+document.addEventListener("DOMContentLoaded", () => {
+
+  // Detect the lang & initialize, based on the browser or "language" item from localstorage
+  jsI18n.detectLanguage();
+  
+  /*
+    recursivePopulate(DOMElement)
+    Will listen for the populate event of any sib element
+    Process the changed node every time it populate
+    Recursively add a populate listener for children elements
+  */
+  function recursivePopulate(element) {
+    Array.from(element.querySelectorAll('*')).forEach((e) => {
+      e.addEventListener("populate", (e) => {
+        recursivePopulate(e.target);
+        jsI18n.processNode(e.target);
+      });
+    });
+  }
+  // Process every children from document
+  recursivePopulate(document);
+});