chore: migrate to typescript

web3.js/src/fee-calculator.ts

@@ -0,0 +1,17 @@
+// @ts-ignore
+import * as BufferLayout from 'buffer-layout';
+
+/**
+ * https://github.com/solana-labs/solana/blob/90bedd7e067b5b8f3ddbb45da00a4e9cabb22c62/sdk/src/fee_calculator.rs#L7-L11
+ *
+ * @internal
+ */
+export const FeeCalculatorLayout = BufferLayout.nu64('lamportsPerSignature');
+
+/**
+ * Calculator for transaction fees.
+ */
+export interface FeeCalculator {
+  /** Cost in lamports to validate a signature. */
+  lamportsPerSignature: number;
+}