CODEWITHSUNDEEP
javascriptnode.jspromisechaining
Mohammad Abdullah
Mohammad Abdullah

Reputation: 31

how could I abort JavaScript Promise?

I am working On NodeJS Project , I used Promise In my code to chain some methods , I needed to abort in one of the 'thens' chain 

findEmployeeByCW('11111', "18-09-2016").
then(function () {
    return findEmployeeByCWE('111111', "18-09-2016", '111111')
}, function () {
    console.log('createEmployeeLoginBy')
    createEmployeeLoginBy('111111', "18-09-2016", '111111').
    then(function (log) {
        SaveEmployeeLogToDb(log)
        // ***************
        // ^_^ I need to exit here ....
    })
})
.then(function (log) {
    return updateLoginTimeTo(log, '08-8668', '230993334')
}, function () {
    return createNewEmployeeLog('224314', "18-09-2016",
        '230993334', '08-99')
})
.then(SaveEmployeeLogToDb).then(DisplayLog).catch(function (e) {
    console.log(e);
})

Upvotes: 1

Views: 425

Answers (2)

Roamer-1888
Roamer-1888

Reputation: 19296

If I understand the intention correctly, there is no need here to cancel or throw.

You should be able to achieve your ends by rearrangement :

findEmployeeByCW('11111', "18-09-2016")
.then(function() {
    return findEmployeeByCWE('111111', "18-09-2016", '111111')
    .then(function(log) {
        return updateLoginTimeTo(log, '08-8668', '230993334');
    }, function(e) {
        return createNewEmployeeLog('224314', "18-09-2016", '230993334', '08-99');
    });
}, function(e) {
    return createEmployeeLoginBy('111111', "18-09-2016", '111111');
})
.then(SaveEmployeeLogToDb)
.then(DisplayLog)
.catch(function(e) {
    console.log(e);
});

That should work with the proviso that a log object is always delivered to SaveEmployeeLogToDb via all possible paths to that point, as implied by the original code.

Upvotes: 2

Stas Parshin
Stas Parshin

Reputation: 1673

You can't currently "cancel" promises. But you can use an exception for that purpose:

findEmployeeByCW('11111', "18-09-2016").
then(function () {
return findEmployeeByCWE('111111', "18-09-2016", '111111')
}, function () {
console.log('createEmployeeLoginBy')

//*** "return" added
return createEmployeeLoginBy('111111', "18-09-2016", '111111').
then(function (log) {
SaveEmployeeLogToDb(log)

//****
throw new Error('promise_exit');
//****

})
})
.then(function (log) {
return updateLoginTimeTo(log, '08-8668', '230993334')
}, function () {
return createNewEmployeeLog('224314', "18-09-2016",
'230993334', '08-99')
})
.then(SaveEmployeeLogToDb).then(DisplayLog).catch(function (e) {

//****
//Only log if it's not an intended exit
if(e.message != 'promise_exit'){
    console.log(e);
}
//****

})

Upvotes: 0

Related Questions