ADDS convenience method to get wrapped token for chain

Author: johnrjj

src/sdk/v4/NftSwapV4.ts

@@ -56,6 +56,7 @@ import {
 } from './orderbook';
 import { DIRECTION_MAPPING, OrderStatusV4, TradeDirection } from './enums';
 import { CONTRACT_ORDER_VALIDATOR } from './properties';
+import { getWrappedNativeToken } from '../../utils/addresses';
 
 export enum SupportedChainIdsV4 {
   Mainnet = 1,
@@ -347,6 +348,10 @@ class NftSwapV4 implements INftSwapV4 {
     );
   }
 
+  getWrappedTokenAddress = (chainId: number | string) => {
+    return getWrappedNativeToken(chainId);
+  }
+
   buildCollectionBasedOrder = (
     erc20ToSell: UserFacingERC20AssetDataSerializedV4,
     nftCollectionToBid: {

src/utils/addresses.ts

@@ -0,0 +1,13 @@
+import { SupportedChainIdsV4 } from '../sdk';
+import defaultAddresses from '../sdk/v4/addresses.json';
+
+export const getWrappedNativeToken = (
+  chainId: number | string
+): string | null => {
+  const chainIdString = chainId.toString(10);
+  const zeroExAddresses:
+    | { exchange: string; wrappedNativeToken: string }
+    | undefined =
+    defaultAddresses[chainIdString as unknown as SupportedChainIdsV4];
+  return zeroExAddresses?.wrappedNativeToken ?? null;
+};