Allowing cancellation in an async function

CancellableAsyncFunction.js

//helper function to use in the async function containing multiple async calls
function checkCancelation(cancelationToken){
    if (cancelationToken && cancelationToken.reject){
        console.log("throwing");
        throw new Error("Rejection forced");
    }
    if (cancelationToken && cancelationToken.cancel){
        console.log("cancelling");
        //return a Promise that never resolves
        return new Promise(()=>{});
    }

    return false;
}

//sample async functions
function getLastMessageId(){
	return new Promise(res => {
		setTimeout(() => res(111), 1500);
	});
}

function getMessageText(id){
	return new Promise(res => {
		setTimeout(() => res("this is the last message"), 1500);
	});
}

function formatText(txt){
	let formattedTxt = `[[${txt}]]`; 
	return new Promise(res => {
		setTimeout(() => res(formattedTxt), 1500);
	});
}

//async function allowing cancellation
async function getLastMessageFormatted(cancelationToken){
    let id = await (checkCancelation(cancelationToken) 
        || getLastMessageId());
    console.log("ID obtained");
    
    let txt = await (checkCancelation(cancelationToken)
        || getMessageText(id));
    console.log("Message obtained");

    let msg = await (checkCancelation(cancelationToken)
        || formatText(txt));
    console.log("Message formatted");

    return msg;
} 

//async main
(async () => {
    console.log("-- test 1");
    let msg = await getLastMessageFormatted();
    console.log("message: " + msg);

    
    console.log("-- test 2");
    let cancellationToken = {};
    //reject after 1 second
    setTimeout(() => cancellationToken.reject = true, 1000);
    try{
        msg = await getLastMessageFormatted(cancellationToken);
        console.log("message: " + msg);
    }
    catch (ex){
        console.error("Exception: " + ex.message);
    }

    console.log("-- test 3");
    cancellationToken = {};
    //cancel after 1 second
    setTimeout(() => cancellationToken.cancel = true, 1000);

    //when cancelling we return a simple Promise, that won't keep the program running 
    //(it's real IO-timeout calls, not the Promise itself, what keeps the node.js loop running)
    //If I just want to keep it running longer, just use this keep alive timeout
    setTimeout(() => console.log("keep alive finished"), 10000);
    try{
        msg = await getLastMessageFormatted(cancellationToken);
        console.log("message: " + msg);
    }
    catch (ex){
        console.error("Exception: " + ex.message);
    }
})();