refactored options_init to options on frontend

src/public/javascripts/services/options.js

@@ -0,0 +1,73 @@
+import server from "./server.js";
+
+let optionsReady;
+
+const loadListeners = [];
+
+class Options {
+    constructor(arr) {
+        this.arr = arr;
+    }
+
+    get(key) {
+        return this.arr[key];
+    }
+
+    getJson(key) {
+        try {
+            return JSON.parse(this.arr[key]);
+        }
+        catch (e) {
+            return null;
+        }
+    }
+
+    getInt(key) {
+        return parseInt(this.arr[key]);
+    }
+
+    getFloat(key) {
+        return parseFloat(this.arr[key]);
+    }
+
+    is(key) {
+        return this.arr[key] === 'true';
+    }
+}
+
+function reloadOptions() {
+    optionsReady = new Promise((resolve, reject) => {
+        server.get('options').then(optionArr => {
+            const options = new Options(optionArr);
+
+            resolve(options);
+
+            for (const listener of loadListeners) {
+                listener(options);
+            }
+        });
+    });
+
+    return optionsReady;
+}
+
+/** just waits for some options without triggering reload */
+async function waitForOptions() {
+    return await optionsReady;
+}
+
+reloadOptions(); // initial load
+
+function addLoadListener(listener) {
+    loadListeners.push(listener);
+
+    // useful when listener has been added after the promise resolved, but can cause double emit if not yet
+    // that should not be an issue though
+    optionsReady.then(listener);
+}
+
+export default {
+    addLoadListener,
+    reloadOptions,
+    waitForOptions
+}