async triggers for either interval or next due, accept cron

server/ajax/form/cron.go

@@ -0,0 +1,17 @@
+package form
+
+import (
+	"time"
+
+	"github.com/robfig/cron/v3"
+)
+
+type Cron string
+
+func (c Cron) Next() time.Time {
+	schedule, err := cron.ParseStandard(string(c))
+	if err != nil {
+		return time.Time{}
+	}
+	return schedule.Next(time.Now())
+}