a start with polyfill

webpack/mailgo.dist.dark.ts

@@ -1,5 +1,6 @@
 // webpack > dist/mailgo.min.js
 
+import mailgoPolyfill from "./polyfill";
 import mailgo from "../src/mailgo";
 
 // call init mailgo attached to the event DOMContentLoaded
@@ -8,4 +9,6 @@ const mailgoConfig = {
   dark: true,
 };
 
+mailgoPolyfill();
+
 mailgo(mailgoConfig);

webpack/mailgo.dist.ts

@@ -1,5 +1,6 @@
 // webpack > dist/mailgo.min.js
 
+import mailgoPolyfill from "./polyfill";
 import mailgo from "../src/mailgo";
 
 // call init mailgo attached to the event DOMContentLoaded
@@ -7,4 +8,6 @@ const mailgoConfig = {
   initEvent: "DOMContentLoaded",
 };
 
+mailgoPolyfill();
+
 mailgo(mailgoConfig);

webpack/polyfill.js

@@ -0,0 +1,43 @@
+// polyfill for mailgo
+
+export default mailgoPolyfill = () => {
+  if (!Array.prototype.includes) {
+    Array.prototype.includes = function (searchElement /*, fromIndex*/) {
+      "use strict";
+      if (this == null) {
+        throw new TypeError(
+          "Array.prototype.includes called on null or undefined"
+        );
+      }
+
+      var O = Object(this);
+      var len = parseInt(O.length, 10) || 0;
+      if (len === 0) {
+        return false;
+      }
+      var n = parseInt(arguments[1], 10) || 0;
+      var k;
+      if (n >= 0) {
+        k = n;
+      } else {
+        k = len + n;
+        if (k < 0) {
+          k = 0;
+        }
+      }
+      var currentElement;
+      while (k < len) {
+        currentElement = O[k];
+        if (
+          searchElement === currentElement ||
+          (searchElement !== searchElement && currentElement !== currentElement)
+        ) {
+          // NaN !== NaN
+          return true;
+        }
+        k++;
+      }
+      return false;
+    };
+  }
+};