fix(url-sync): Makes url sync more reliable

2 main changes here :
 - the url-sync internal widget now relies on the helper directly and
   not on the instantsearch lifecycle anymore.
 - there is dedicated channel of update for the changes coming from the
   history (private API for the moment)

FIX #730
FIX #729

Author: Alexandre Stanislawski

dev/app.js

@@ -5,9 +5,7 @@ var search = instantsearch({
   appId: 'latency',
   apiKey: '6be0576ff61c053d5f9a3225e2a90f76',
   indexName: 'instant_search',
-  urlSync: {
-    useHash: true
-  }
+  urlSync: true
 });
 
 search.addWidget(
@@ -281,3 +279,4 @@ search.addWidget(
 );
 
 search.start();
+

src/lib/InstantSearch.js

@@ -5,7 +5,7 @@ import forEach from 'lodash/collection/forEach';
 import merge from 'lodash/object/merge';
 import union from 'lodash/array/union';
 
-let EventEmitter = require('events').EventEmitter;
+import {EventEmitter} from 'events';
 
 import urlSyncWidget from './url-sync.js';
 import version from './version.js';
@@ -20,7 +20,8 @@ function defaultCreateURL() { return '#'; }
  * @param  {string} [options.numberLocale] The locale used to display numbers. This will be passed
  * to Number.prototype.toLocaleString()
  * @param  {Object} [options.searchParameters] Additional parameters to pass to
- * the Algolia API. [Full documentation](https://community.algolia.com/algoliasearch-helper-js/docs/SearchParameters.html)
+ * the Algolia API.
+ * [Full documentation](https://community.algolia.com/algoliasearch-helper-js/docs/SearchParameters.html)
  * @param  {Object|boolean} [options.urlSync] Url synchronization configuration.
  * Setting to `true` will synchronize the needed search parameters with the browser url.
  * @param  {string[]} [options.urlSync.trackedParameters] Parameters that will
@@ -66,7 +67,7 @@ Usage: instantsearch({
       helpers: require('./helpers.js')({numberLocale}),
       compileOptions: {}
     };
-    this.urlSync = urlSync;
+    this.urlSync = urlSync === true ? {} : urlSync;
   }
 
   /**
@@ -93,8 +94,12 @@ Usage: instantsearch({
     if (this.urlSync) {
       let syncWidget = urlSyncWidget(this.urlSync);
       this._createURL = syncWidget.createURL.bind(syncWidget);
+      this._onHistoryChange = syncWidget.onHistoryChange.bind(syncWidget);
       this.widgets.push(syncWidget);
-    } else this._createURL = defaultCreateURL;
+    } else {
+      this._createURL = defaultCreateURL;
+      this._onHistoryChange = function() {};
+    }
 
     this.searchParameters = this.widgets.reduce(enhanceConfiguration, this.searchParameters);
 
@@ -136,10 +141,10 @@ Usage: instantsearch({
   }
 
   _init(state, helper) {
+    const {_onHistoryChange, templatesConfig} = this;
     forEach(this.widgets, function(widget) {
       if (widget.init) {
-        const templatesConfig = this.templatesConfig;
-        widget.init({state, helper, templatesConfig});
+        widget.init({state, helper, templatesConfig, onHistoryChange: _onHistoryChange});
       }
     }, this);
   }

src/lib/__tests__/InstantSearch-test.js

@@ -39,7 +39,12 @@ describe('InstantSearch lifecycle', () => {
     apiKey = 'apiKey';
     indexName = 'lifecycle';
 
-    searchParameters = {some: 'configuration', values: [-2, -1], index: indexName, another: {config: 'parameter'}};
+    searchParameters = {
+      some: 'configuration',
+      values: [-2, -1],
+      index: indexName,
+      another: {config: 'parameter'}
+    };
 
     InstantSearch.__Rewire__('algoliasearch', algoliasearch);
     InstantSearch.__Rewire__('algoliasearchHelper', algoliasearchHelper);
@@ -113,7 +118,12 @@ describe('InstantSearch lifecycle', () => {
           .toEqual([
             client,
             indexName,
-            {some: 'modified', values: [-2, -1], index: indexName, another: {different: 'parameter', config: 'parameter'}}
+            {
+              some: 'modified',
+              values: [-2, -1],
+              index: indexName,
+              another: {different: 'parameter', config: 'parameter'}
+            }
           ]);
       });
 
@@ -125,12 +135,11 @@ describe('InstantSearch lifecycle', () => {
         expect(widget.init.calledOnce).toBe(true, 'widget.init called once');
         expect(widget.init.calledAfter(widget.getConfiguration))
           .toBe(true, 'widget.init() was called after widget.getConfiguration()');
-        expect(widget.init.args[0][0]).
-          toEqual({
-            state: helper.state,
-            helper,
-            templatesConfig: search.templatesConfig
-          });
+        const args = widget.init.args[0][0];
+        expect(args.state).toBe(helper.state);
+        expect(args.helper).toBe(helper);
+        expect(args.templatesConfig).toBe(search.templatesConfig);
+        expect(args.onHistoryChange).toBe(search._onHistoryChange);
       });
 
       it('does not call widget.render', () => {

src/lib/url-sync.js

@@ -1,6 +1,7 @@
 import algoliasearchHelper from 'algoliasearch-helper';
 let AlgoliaSearchHelper = algoliasearchHelper.AlgoliaSearchHelper;
 let majorVersionNumber = require('../lib/version.js').split('.')[0];
+import urlHelper from 'algoliasearch-helper/src/url';
 
 import isEqual from 'lodash/lang/isEqual';
 import merge from 'lodash/object/merge';
@@ -104,42 +105,42 @@ class URLSync {
     return config;
   }
 
-  onPopState(helper) {
-    let qs = this.urlUtils.readUrl();
-    let partialState = AlgoliaSearchHelper.getConfigurationFromQueryString(qs);
-    let fullState = merge({}, this.originalConfig, partialState);
+  init({helper}) {
+    helper.on('change', (state) => {
+      this.renderURLFromState(state);
+    });
+    this.onHistoryChange(this.onPopState.bind(this, helper));
+  }
+
+  onPopState(helper, fullState) {
     // compare with helper.state
     let partialHelperState = helper.getState(this.trackedParameters);
     let fullHelperState = merge({}, this.originalConfig, partialHelperState);
 
     if (isEqual(fullHelperState, fullState)) return;
 
-    helper.setState(fullState).search();
+    helper.overrideStateWithoutTriggeringChangeEvent(fullState).search();
   }
 
-  init({helper}) {
-    this.urlUtils.onpopstate(this.onPopState.bind(this, helper));
-  }
-
-  render({helper}) {
-    let helperState = helper.getState(this.trackedParameters);
+  renderURLFromState(state) {
     let currentQueryString = this.urlUtils.readUrl();
-    let urlState = AlgoliaSearchHelper.getConfigurationFromQueryString(currentQueryString);
-
-    if (isEqual(helperState, urlState)) return;
-
-    // Add instantsearch version to reconciliate old url with newer versions
     let foreignConfig = AlgoliaSearchHelper.getForeignConfigurationInQueryString(currentQueryString);
     foreignConfig.is_v = majorVersionNumber;
 
-    let qs = helper.getStateAsQueryString({filters: this.trackedParameters, moreAttributes: foreignConfig});
+    let qs = urlHelper.getQueryStringFromState(
+      state.filter(this.trackedParameters),
+      {moreAttributes: foreignConfig}
+    );
+
     if (this.timer() < this.threshold) {
       this.urlUtils.replaceState(qs);
     } else {
       this.urlUtils.pushState(qs);
     }
   }
 
+  // External API's
+
   createURL(state) {
     let currentQueryString = this.urlUtils.readUrl();
     let filteredState = state.filter(this.trackedParameters);
@@ -149,6 +150,15 @@ class URLSync {
 
     return this.urlUtils.createURL(algoliasearchHelper.url.getQueryStringFromState(filteredState));
   }
+
+  onHistoryChange(fn) {
+    this.urlUtils.onpopstate(() => {
+      let qs = this.urlUtils.readUrl();
+      let partialState = AlgoliaSearchHelper.getConfigurationFromQueryString(qs);
+      let fullState = merge({}, this.originalConfig, partialState);
+      fn(fullState);
+    });
+  }
 }
 
 /**