feature: vor und nachteile

praesentation/node_modules/dayjs/esm/plugin/weekday/index.js

@@ -0,0 +1,15 @@
+export default (function (o, c) {
+  var proto = c.prototype;
+
+  proto.weekday = function (input) {
+    var weekStart = this.$locale().weekStart || 0;
+    var $W = this.$W;
+    var weekday = ($W < weekStart ? $W + 7 : $W) - weekStart;
+
+    if (this.$utils().u(input)) {
+      return weekday;
+    }
+
+    return this.subtract(weekday, 'day').add(input, 'day');
+  };
+});