4 files changed, 32 insertions, 4 deletions
diff --git a/packages/0x.js/CHANGELOG.md b/packages/0x.js/CHANGELOG.md
index 5250402c6..06b11cba8 100644
--- a/packages/0x.js/CHANGELOG.md
+++ b/packages/0x.js/CHANGELOG.md
@@ -1,8 +1,12 @@
 # CHANGELOG
 
+## v0.x.0 - _TBD, 2018_
+
+    * Add `zeroEx.etherToken.getContractAddressIfExists` (#350)
+
 ## v0.31.1 - _February 1, 2018_
 
-    * Fix the bug causing order watcher to throw is makerToken === zrx (#357)
+    * Fix the bug causing order watcher to throw if makerToken === zrx (#357)
 
 ## v0.31.0 - _January 30, 2018_
 
diff --git a/packages/0x.js/src/contract_wrappers/contract_wrapper.ts b/packages/0x.js/src/contract_wrappers/contract_wrapper.ts
index 2d5818618..d913e8d9b 100644
--- a/packages/0x.js/src/contract_wrappers/contract_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/contract_wrapper.ts
@@ -32,7 +32,7 @@ const CONTRACT_NAME_TO_NOT_FOUND_ERROR: {
 
 export class ContractWrapper {
     protected _web3Wrapper: Web3Wrapper;
-    private _networkId: number;
+    protected _networkId: number;
     private _abiDecoder?: AbiDecoder;
     private _blockAndLogStreamerIfExists?: BlockAndLogStreamer;
     private _blockAndLogStreamIntervalIfExists?: NodeJS.Timer;
diff --git a/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts b/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts
index cbafcfe94..32c9ae6a9 100644
--- a/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts
@@ -162,6 +162,19 @@ export class EtherTokenWrapper extends ContractWrapper {
     public _unsubscribeAll(): void {
         super._unsubscribeAll();
     }
+    /**
+     * Retrieves the Ethereum address of the EtherToken contract deployed on the network
+     * that the user-passed web3 provider is connected to. If it's not Kovan, Ropsten, Rinkeby, Mainnet or TestRPC
+     * (networkId: 50), it will return undefined (e.g a private network).
+     * @returns The Ethereum address of the EtherToken contract or undefined.
+     */
+    public getContractAddressIfExists(): string | undefined {
+        const networkSpecificArtifact = artifacts.EtherTokenArtifact.networks[this._networkId];
+        const contractAddressIfExists = _.isUndefined(networkSpecificArtifact)
+            ? undefined
+            : networkSpecificArtifact.address;
+        return contractAddressIfExists;
+    }
     private _invalidateContractInstance(): void {
         this._unsubscribeAll();
         this._etherTokenContractsByAddress = {};
diff --git a/packages/0x.js/test/ether_token_wrapper_test.ts b/packages/0x.js/test/ether_token_wrapper_test.ts
index 9716abab8..da49ec467 100644
--- a/packages/0x.js/test/ether_token_wrapper_test.ts
+++ b/packages/0x.js/test/ether_token_wrapper_test.ts
@@ -17,7 +17,6 @@ import {
     ZeroEx,
     ZeroExError,
 } from '../src';
-import { artifacts } from '../src/artifacts';
 import { DoneCallback } from '../src/types';
 
 import { chaiSetup } from './utils/chai_setup';
@@ -60,7 +59,7 @@ describe('EtherTokenWrapper', () => {
         tokens = await zeroEx.tokenRegistry.getTokensAsync();
         userAddresses = await zeroEx.getAvailableAddressesAsync();
         addressWithETH = userAddresses[0];
-        wethContractAddress = (zeroEx.etherToken as any)._getContractAddress(artifacts.EtherTokenArtifact);
+        wethContractAddress = zeroEx.etherToken.getContractAddressIfExists() as string;
         depositWeiAmount = (zeroEx as any)._web3Wrapper.toWei(new BigNumber(5));
         decimalPlaces = 7;
         addressWithoutFunds = userAddresses[1];
@@ -71,6 +70,18 @@ describe('EtherTokenWrapper', () => {
     afterEach(async () => {
         await blockchainLifecycle.revertAsync();
     });
+    describe('#getContractAddressIfExists', async () => {
+        it('should return contract address if connected to a known network', () => {
+            const contractAddressIfExists = zeroEx.etherToken.getContractAddressIfExists();
+            expect(contractAddressIfExists).to.not.be.undefined();
+        });
+        it('should return undefined if connected to an unknown network', () => {
+            const UNKNOWN_NETWORK_NETWORK_ID = 10;
+            const unknownNetworkZeroEx = new ZeroEx(web3.currentProvider, { networkId: UNKNOWN_NETWORK_NETWORK_ID });
+            const contractAddressIfExists = unknownNetworkZeroEx.etherToken.getContractAddressIfExists();
+            expect(contractAddressIfExists).to.be.undefined();
+        });
+    });
     describe('#depositAsync', () => {
         it('should successfully deposit ETH and issue Wrapped ETH tokens', async () => {
             const preETHBalance = await (zeroEx as any)._web3Wrapper.getBalanceInWeiAsync(addressWithETH);