fix(csv-exporter): use arrays instead of strings to build data #6673

Author: onlyexeption

projects/igniteui-angular/ng-package.json

@@ -8,7 +8,7 @@
   "whitelistedNonPeerDependencies": [
       "@types/hammerjs",
       "@types/jszip",
-      "core-js",
+      "core-js-pure",
       "hammerjs",
       "jszip",
       "resize-observer-polyfill",

projects/igniteui-angular/ng-package.prod.json

@@ -10,7 +10,7 @@
   "whitelistedNonPeerDependencies": [
       "@types/hammerjs",
       "@types/jszip",
-      "core-js",
+      "core-js-pure",
       "hammerjs",
       "jszip",
       "resize-observer-polyfill",

projects/igniteui-angular/src/lib/services/csv/char-separated-value-data.ts

@@ -85,23 +85,26 @@ export class CharSeparatedValueData {
     }
 
     private processDataRecords(currentData, keys, escapeChars) {
-        let dataRecords = '';
-        for (const row of currentData) {
-            dataRecords += this.processRecord(row, keys, escapeChars);
+        const dataRecords = new Array(currentData.length);
+
+        for (let i = 0; i < currentData.length; i++) {
+            const row = currentData[i]
+            dataRecords[i] = this.processRecord(row, keys, escapeChars);
         }
 
-        return dataRecords;
+        return dataRecords.join('');
     }
 
     private processDataRecordsAsync(currentData, keys, escapeChars, done: (result: string) => void) {
-        let dataRecords = '';
+        const dataRecords = new Array(currentData.length);
+
         yieldingLoop(currentData.length, 1000,
             (i) => {
                 const row = currentData[i];
-                dataRecords += this.processRecord(row, keys, escapeChars);
+                dataRecords[i] = this.processRecord(row, keys, escapeChars);
             },
             () => {
-                done(dataRecords);
+                done(dataRecords.join(''));
             });
     }