Implement formatters caching to improve performance

Author: nightskylark

src/date.js

@@ -22,8 +22,18 @@ var getIntlFormatter = function(format) {
     };
 };
 
+var formattersCache = {};
+var getFormatter = function(format) {
+    var key = locale() + '/' + JSON.stringify(format);
+    if(!formattersCache[key]) {
+        formattersCache[key] = (new Intl.DateTimeFormat(locale(), format)).format;
+    }
+    
+    return formattersCache[key];
+};
+
 var formatDateTime = function(date, format) {
-    return (new Intl.DateTimeFormat(locale(), format)).format(date).replace(SYMBOLS_TO_REMOVE_REGEX, '');
+    return getFormatter(format)(date).replace(SYMBOLS_TO_REMOVE_REGEX, '');
 };
 
 var formatNumber = function(number) {

src/number.js

@@ -7,8 +7,14 @@ var compareVersions = require('devextreme/core/utils/version').compare;
 
 var currencyOptionsCache = {},
     detectCurrencySymbolRegex = /([^\s0]+)?(\s*)0*[.,]*0*(\s*)([^\s0]+)?/,
+    formattersCache = {},
     getFormatter = function(format) {
-        return (new Intl.NumberFormat(locale(), format)).format;
+        var key = locale() + '/' + JSON.stringify(format);
+        if(!formattersCache[key]) {
+            formattersCache[key] = (new Intl.NumberFormat(locale(), format)).format;
+        }
+        
+        return formattersCache[key];
     },
     getCurrencyFormatter = function(currency) {
         return (new Intl.NumberFormat(locale(), { style: 'currency', currency: currency }));