fix(urlSync): update url only after threshold (#1917)

Before this commit, our default implementation tried to update
the url at every character. This led to many slowdown reports from users
of the library.

Now we only update the url after the threshold

fixes #1856

Author: vvo

src/lib/url-sync.js

@@ -23,7 +23,6 @@ function timerMaker(t0) {
  * @property {string} character the character used in the url
  * @property {function} onpopstate add an event listener for the URL change
  * @property {function} pushState creates a new entry in the browser history
- * @property {function} replaceState update the current entry of the browser history
  * @property {function} readUrl reads the query string of the parameters
  */
 
@@ -39,9 +38,6 @@ const hashUrlUtils = {
   pushState(qs) {
     window.location.assign(getFullURL(this.createURL(qs)));
   },
-  replaceState(qs) {
-    window.location.replace(getFullURL(this.createURL(qs)));
-  },
   createURL(qs) {
     return window.location.search + this.character + qs;
   },
@@ -62,9 +58,6 @@ const modernUrlUtils = {
   pushState(qs, {getHistoryState}) {
     window.history.pushState(getHistoryState(), '', getFullURL(this.createURL(qs)));
   },
-  replaceState(qs, {getHistoryState}) {
-    window.history.replaceState(getHistoryState(), '', getFullURL(this.createURL(qs)));
-  },
   createURL(qs) {
     return this.character + qs + document.location.hash;
   },
@@ -95,9 +88,6 @@ class URLSync {
     this.mapping = options.mapping || {};
     this.getHistoryState = options.getHistoryState || (() => null);
     this.threshold = options.threshold || 700;
-    this.updateOnEveryKeyStroke = options.updateOnEveryKeyStroke !== undefined ?
-      options.updateOnEveryKeyStroke :
-      true;
     this.trackedParameters = options.trackedParameters || ['query', 'attribute:*', 'index', 'page', 'hitsPerPage'];
 
     this.searchParametersFromUrl = AlgoliaSearchHelper
@@ -154,15 +144,6 @@ class URLSync {
       }
     );
 
-    if (this.updateOnEveryKeyStroke === true) {
-      if (this.timer() < this.threshold) {
-        this.urlUtils.replaceState(qs, {getHistoryState: this.getHistoryState});
-      } else {
-        this.urlUtils.pushState(qs, {getHistoryState: this.getHistoryState});
-      }
-      return;
-    }
-
     clearTimeout(this.urlUpdateTimeout);
     this.urlUpdateTimeout = setTimeout(() => {
       this.urlUtils.pushState(qs, {getHistoryState: this.getHistoryState});