added polling class

src/lib/polling.ts

@@ -0,0 +1,49 @@
+type callback = (...args: any[]) => void
+
+class Polling {
+    private static instance: Polling;
+    private timeoutID: number;
+    private delay: number = 1000;
+    private enabled: boolean = false;
+    constructor() {
+        this.enabled = false;
+    }
+    static create(): Polling {
+        this.instance = this.instance || new Polling();
+        return this.instance;
+    }
+
+    enable() {
+        this.enabled = true;
+        return this;
+    }
+    disable() {
+        this.enabled = false;
+        return this;
+    }
+    isEnabled() {
+        return this.enabled;
+    }
+    setDelay(time: number): Polling {
+        this.delay = time;
+        return this;
+    }
+
+    run(callback: callback, ...args: any[]) {
+        this.clear().enable()
+        callback(...args);
+        let timeoutHandler = () => {
+            if (this.enabled) {
+                this.run(callback, ...args);
+            }
+        }
+        this.timeoutID = window.setTimeout(timeoutHandler, this.delay);
+    }
+    clear() {
+        if (this.timeoutID)
+            window.clearTimeout(this.timeoutID);
+        return this;
+    }
+}
+
+export default Polling;