the default locale months and days names
webix.i18n.calendar: {
monthFull:["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"],
monthShort:["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"],
dayFull:["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"],
dayShort:["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"]
}
webix.i18n.setLocale("en-US");
You need to call setLocale to apply the new format settings