Add const example to app-js (#1424)

* Add const example to app-js

* Trigger Travis

packages/app-js/src/snippets/consts-examples.ts

@@ -0,0 +1,20 @@
+// Copyright 2017-2019 @polkadot/app-js authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import { Snippet } from '@polkadot/app-js/types';
+
+export const constsStakingParameters: Snippet = {
+  value: 'constsStakingParameters',
+  text: 'Get staking parameters',
+  label: { color: 'green', children: 'Consts', size: 'tiny' },
+  code: `// Get SRML staking parameters as consts
+// 'parameter_types' were added to substrate with spec_version: 101.
+// This example will throw an error if used with versions before that.
+
+const bondingDuration = api.consts.staking.bondingDuration;
+const sessionsPerEra = api.consts.staking.sessionsPerEra;
+
+console.log('Staking bonding duration: ' + bondingDuration);
+console.log('Staking sessions per era: ' + sessionsPerEra);`
+};

packages/app-js/src/snippets/index.ts

@@ -19,7 +19,13 @@ import {
   storageRetrieveInfoOnQueryKeys
 } from './storage-examples';
 
-import { extrinsicMakeTransfer } from './extrinsics-examples';
+import {
+  constsStakingParameters
+} from './consts-examples';
+
+import {
+  extrinsicMakeTransfer
+} from './extrinsics-examples';
 
 const snippets: Snippet[] = [
   rpcNetworkAuthoring,
@@ -31,6 +37,7 @@ const snippets: Snippet[] = [
   storageListenToBalanceChange,
   storageListenToMultipleBalancesChange,
   storageRetrieveInfoOnQueryKeys,
+  constsStakingParameters,
   extrinsicMakeTransfer
 ];
 

packages/app-js/src/snippets/storage-examples.ts

@@ -9,17 +9,16 @@ export const storageGetInfo: Snippet = {
   text: 'Get chain state information',
   label: { color: 'blue', children: 'Storage', size: 'tiny' },
   code: `// Get chain state information
-// Make our basic chain state/storage queries, all in one go
+// Make our basic chain state / storage queries, all in one go
 
-const [minimumValidatorCount, validators] = await Promise.all([
+const [now, minimumValidatorCount, validators] = await Promise.all([
+  api.query.timestamp.now(),
   api.query.staking.minimumValidatorCount(),
   api.query.session.validators()
 ]);
 
-const transferFee = api.consts.balances.transferFee;
-
+console.log('The current date is: ' + now);
 console.log('The minimum validator count: ' + minimumValidatorCount);
-console.log('transfer fee: ', transferFee);
 
 if (validators && validators.length > 0) {
   // Retrieve the balances for all validators