There are 2 different examples how to use confirm:
kendo.confirm(
"Are you sure that you want to proceed?"
).then(
function
() {
//from online demos
kendo.confirm("Are you sure that you want to proceed?").done(function () { //from online documentation
But kendo.all.d.ts has:
function
confirm(text: string): void;
which makes it impossible (without typecasting to any) for chaining (then/done). Same for prompt.