So siehts ganz gut aus !

node_modules/es5-ext/array/#/find-index/is-implemented.js

@@ -0,0 +1,11 @@
+"use strict";
+
+var fn = function (value) {
+	return value > 3;
+};
+
+module.exports = function () {
+	var arr = [1, 2, 3, 4, 5, 6];
+	if (typeof arr.findIndex !== "function") return false;
+	return arr.findIndex(fn) === 3;
+};