feat: added refs, refactored UINode for more concise build functions

src/Ref.ts

@@ -0,0 +1,39 @@
+export default class Ref<T extends { toString(): string } | string | null = string> {
+    private watchers: Array<(newVal: T) => void> | null = null;
+    private value: T;
+    private asString?: string;
+    private isString: boolean;
+
+    constructor(val: T) {
+        this.value = val;
+        this.isString = typeof val === "string";
+    }
+
+    watch(callback: (newVal: T) => void): void {
+        if (this.watchers === null) {
+            this.watchers = [];
+        }
+        this.watchers.push(callback);
+    }
+
+    get val(): T {
+        return this.value;
+    }
+
+    set val(val: T) {
+        this.watchers?.forEach(watcher => watcher(val));
+        this.value = val;
+    }
+
+    toString(): string {
+        if (!this.asString) {
+            if (this.isString) {
+                return this.val as unknown as string;
+            } else {
+                this.asString = this.val?.toString() ?? "null";
+            }
+        }
+        return this.asString;
+    }
+}
+