phase-6: typescript introduction

server/screener/assets/Etf.ts

@@ -0,0 +1,47 @@
+import { Asset } from './Asset.js';
+
+interface EtfData {
+  ticker?: string;
+  currentPrice?: number;
+  expenseRatio?: string | number;
+  totalAssets?: string | number;
+  yield?: string | number;
+  volume?: string | number;
+  fiveYearReturn?: string | number;
+  [key: string]: unknown;
+}
+
+export interface EtfMetrics {
+  expenseRatio: number;
+  totalAssets: number;
+  yield: number;
+  volume: number;
+  fiveYearReturn: number;
+}
+
+export class Etf extends Asset {
+  metrics: EtfMetrics;
+
+  constructor(data: EtfData) {
+    super(data);
+    this.metrics = {
+      expenseRatio: parseFloat(String(data.expenseRatio)) || 0,
+      totalAssets: parseFloat(String(data.totalAssets)) || 0,
+      yield: parseFloat(String(data.yield)) || 0,
+      volume: parseFloat(String(data.volume)) || 0,
+      fiveYearReturn: parseFloat(String(data.fiveYearReturn)) || 0,
+    };
+  }
+
+  getDisplayMetrics(): Record<string, string> {
+    return {
+      Ticker: this.ticker,
+      Type: 'ETF',
+      Price: this.formatCurrency(this.currentPrice),
+      'Exp Ratio%': `${this.metrics.expenseRatio.toFixed(2)}%`,
+      'Yield%': `${this.metrics.yield.toFixed(2)}%`,
+      AUM: this.formatLargeNumber(this.metrics.totalAssets),
+      '5Y Return%': `${this.metrics.fiveYearReturn.toFixed(1)}%`,
+    };
+  }
+}