Refactor blocks.ts and index 10k block headers at launch

backend/src/api/transaction-utils.ts

@@ -44,6 +44,14 @@ class TransactionUtils {
     }
     return transactionExtended;
   }
+
+  public hex2ascii(hex: string) {
+    let str = '';
+    for (let i = 0; i < hex.length; i += 2) {
+      str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
+    }
+    return str;
+  }
 }
 
 export default new TransactionUtils();