feat: support pre and post token balances (#13603)

* feat: support pre and post token balances

* fix: define tokenbalance

* fix: change pre/post balances to array

web3.js/src/connection.js

@@ -373,6 +373,12 @@ type ParsedInnerInstruction = {
   instructions: (ParsedInstruction | PartiallyDecodedInstruction)[],
 };
 
+type TokenBalance = {
+  accountIndex: number,
+  mint: string,
+  uiTokenAmount: TokenAmount,
+};
+
 /**
  * Metadata for a parsed confirmed transaction on the ledger
  *
@@ -382,6 +388,8 @@ type ParsedInnerInstruction = {
  * @property {Array<number>} preBalances The balances of the transaction accounts before processing
  * @property {Array<number>} postBalances The balances of the transaction accounts after processing
  * @property {Array<string>} logMessages An array of program log messages emitted during a transaction
+ * @property {Array<TokenBalance>} preTokenBalances The token balances of the transaction accounts before processing
+ * @property {Array<TokenBalance>} postTokenBalances The token balances of the transaction accounts after processing
  * @property {object|null} err The error result of transaction processing
  */
 type ParsedConfirmedTransactionMeta = {
@@ -390,6 +398,8 @@ type ParsedConfirmedTransactionMeta = {
   preBalances: Array<number>,
   postBalances: Array<number>,
   logMessages?: Array<string>,
+  preTokenBalances?: Array<TokenBalance>,
+  postTokenBalances?: Array<TokenBalance>,
   err: TransactionError | null,
 };
 
@@ -1178,6 +1188,36 @@ const ConfirmedTransactionMetaResult = struct.union([
     preBalances: struct.array(['number']),
     postBalances: struct.array(['number']),
     logMessages: struct.union([struct.array(['string']), 'null', 'undefined']),
+    preTokenBalances: struct.union([
+      struct.array([
+        struct.pick({
+          accountIndex: 'number',
+          mint: 'string',
+          uiTokenAmount: struct.pick({
+            amount: 'string',
+            decimals: 'number',
+            uiAmount: 'number',
+          }),
+        }),
+      ]),
+      'null',
+      'undefined',
+    ]),
+    postTokenBalances: struct.union([
+      struct.array([
+        struct.pick({
+          accountIndex: 'number',
+          mint: 'string',
+          uiTokenAmount: struct.pick({
+            amount: 'string',
+            decimals: 'number',
+            uiAmount: 'number',
+          }),
+        }),
+      ]),
+      'null',
+      'undefined',
+    ]),
   }),
 ]);
 /**
@@ -1214,6 +1254,36 @@ const ParsedConfirmedTransactionMetaResult = struct.union([
     preBalances: struct.array(['number']),
     postBalances: struct.array(['number']),
     logMessages: struct.union([struct.array(['string']), 'null', 'undefined']),
+    preTokenBalances: struct.union([
+      struct.array([
+        struct.pick({
+          accountIndex: 'number',
+          mint: 'string',
+          uiTokenAmount: struct.pick({
+            amount: 'string',
+            decimals: 'number',
+            uiAmount: 'number',
+          }),
+        }),
+      ]),
+      'null',
+      'undefined',
+    ]),
+    postTokenBalances: struct.union([
+      struct.array([
+        struct.pick({
+          accountIndex: 'number',
+          mint: 'string',
+          uiTokenAmount: struct.pick({
+            amount: 'string',
+            decimals: 'number',
+            uiAmount: 'number',
+          }),
+        }),
+      ]),
+      'null',
+      'undefined',
+    ]),
   }),
 ]);