Fix for unicode regex in ie/firefox (#408)

Author: nmetulev

src/components/mgt-person/mgt-person.ts

@@ -585,8 +585,7 @@ export class MgtPerson extends MgtTemplatedComponent {
     if (!initials && person.displayName) {
       const name = person.displayName.split(/\s+/);
       for (let i = 0; i < 2 && i < name.length; i++) {
-        if (name[i][0] && name[i][0].match(/\p{L}/gu)) {
-          // check if letter
+        if (name[i][0] && this.isLetter(name[i][0])) {
           initials += name[i][0].toUpperCase();
         }
       }
@@ -595,6 +594,14 @@ export class MgtPerson extends MgtTemplatedComponent {
     return initials;
   }
 
+  private isLetter(char: string) {
+    try {
+      return char.match(new RegExp('\\p{L}', 'u'));
+    } catch (e) {
+      return char.toLowerCase() !== char.toUpperCase();
+    }
+  }
+
   private handleMouseClick(e: MouseEvent) {
     if (this.personCardInteraction === PersonCardInteraction.click) {
       this.showPersonCard();