Add loading of live data

Logic/Web/LiveQueryHandler.ts

@@ -0,0 +1,53 @@
+/**
+ * Fetches data from random data sources
+ */
+import {UIEventSource} from "../UIEventSource";
+import * as $ from "jquery"
+
+export default class LiveQueryHandler {
+
+
+    private static cache = {} // url --> UIEventSource<actual data>
+    private static neededShorthands = {} // url -> (shorthand:paths)[]
+
+    public static FetchLiveData(url: string, shorthands: string[]): UIEventSource<any /* string -> string */> {
+
+        const shorthandsSet: string[] = LiveQueryHandler.neededShorthands[url] ?? []
+
+        for (const shorthand of shorthands) {
+            if (shorthandsSet.indexOf(shorthand) < 0) {
+                shorthandsSet.push(shorthand);
+            }
+        }
+        LiveQueryHandler.neededShorthands[url] = shorthandsSet;
+
+
+        if (LiveQueryHandler[url] === undefined) {
+            const source = new UIEventSource({});
+            LiveQueryHandler[url] = source;
+
+                console.log("Fetching live data from a third-party (unknown) API:",url)
+            $.getJSON(url, function (data) {
+                for (const shorthandDescription of shorthandsSet) {
+
+                    const descr = shorthandDescription.trim().split(":");
+                    const shorthand = descr[0];
+                    const path = descr[1];
+                    const parts = path.split(".");
+                    let trail = data;
+                    for (const part of parts) {
+                        if (trail !== undefined) {
+                            trail = trail[part];
+                        }
+                    }
+                    source.data[shorthand] = trail;
+                }
+                source.ping();
+
+            })
+
+        }
+        return LiveQueryHandler[url];
+    }
+
+}