Add confirmations to TransactionResponse (ethers-io#4094).

src.ts/providers/provider.ts

@@ -1345,6 +1345,26 @@ export class TransactionResponse implements TransactionLike<string>, Transaction
         return this.provider.getTransaction(this.hash);
     }
 
+    /**
+     *  Resolve to the number of confirmations this transaction has.
+     */
+    async confirmations(): Promise<number> {
+        if (this.blockNumber == null) {
+            const { tx, blockNumber } = await resolveProperties({
+                tx: this.getTransaction(),
+                blockNumber: this.provider.getBlockNumber()
+            });
+
+            // Not mined yet...
+            if (tx == null || tx.blockNumber == null) { return 0; }
+
+            return blockNumber - tx.blockNumber + 1;
+        }
+
+        const blockNumber = await this.provider.getBlockNumber();
+        return blockNumber - this.blockNumber + 1;
+    }
+
     /**
      *  Resolves once this transaction has been mined and has
      *  %%confirms%% blocks including it (default: ``1``) with an