Jumping over loop iteration following a JavaScript catch block

Question

Jumping over loop iteration following a JavaScript catch block

Currently, I am developing an API that requires making repeated calls to another API (specifically, Quickbooks Online) within a loop. These calls are encapsulated in promises that either resolve or reject based on the response from Quickbooks. Everything functions as expected, but I am looking for a way to allow the loop to continue execution after handling errors. At present, when an error is caught, it gets logged into the database, but the loop halts and no further calls are executed. I have attempted using "return" and "continue" inside the catch block without success.

Below is an example of the code:

// This is a section of a larger loop. Needs to be asynchronous
await paymentInfo.forEach(async ln => {

        var payRef = ln.payment_ref
        var vendor = ln.vendor_id

        var finalPayment = await service.createPayment(args)
          .then(console.log("Payment created"))
          .catch((err) => { 

            // Log the error to the database
            service.dbUpdate(err)
            .then(console.log("Error Logged to DB"))
            .catch(() => {})

            // How do we proceed from here?
       })
      // Update the database with payment ID here
})

In essence, I simply want to be able to continue to the next iteration of the loop after catching an error. As far as I can see, there isn't a straightforward way to achieve this. Any suggestions would be greatly appreciated.

javascript foreach promise async-await

Answer 1

Answer №1

If you are already using async/await, there is no need for .then method. Simply utilize await and catch errors with a traditional try/catch block. The continue statement will work naturally when placed inside a for loop. However, it appears that you need to handle the loop iterations in parallel, so each iteration should be contained within a function invocation where you can return.

Another issue present is the lack of error handling in your async function due to not being awaited. Instead of awaiting forEach, which does not return anything, one solution is to map your array into an array of promises (the result of executing anonymous async functions) and then await all those promises simultaneously using Promise.all.

await Promise.all(paymentInfo.map(ln => (async () => {
        var payRef = ln.payment_ref
        var vendor = ln.vendor_id

        try {
            var finalPayment = await service.createPayment(args)
            console.log("Payment created")
        } catch (err) {
            // Log error to DB
            try {
                await service.dbUpdate(err)
                console.log("Error Logged to DB"))
            } catch (e) {}

           return
        }

       // Database update here with payment ID
})())

It may be unnecessary to have a continue statement if the only purpose was to react to the possibility of a payment not being created. In such case, you would simply use the payment value unconditionally, as any error thrown would skip the rest of the try block anyway!

await Promise.all(paymentInfo.map((async ln => {
        var payRef = ln.payment_ref
        var vendor = ln.vendor_id

        try {
            var finalPayment = await service.createPayment(args)
            console.log("Payment created")

            // Database update here with payment ID
        } catch (err) {
            // Log error to DB
            try {
                await service.dbUpdate(err)
                console.log("Error Logged to DB"))
            } catch (e) {}
        }
})())

Answer 2

If you are already using async/await, there is no need for .then method. Simply utilize await and catch errors with a traditional try/catch block. The continue statement will work naturally when placed inside a for loop. However, it appears that you need to handle the loop iterations in parallel, so each iteration should be contained within a function invocation where you can return.

Another issue present is the lack of error handling in your async function due to not being awaited. Instead of awaiting forEach, which does not return anything, one solution is to map your array into an array of promises (the result of executing anonymous async functions) and then await all those promises simultaneously using Promise.all.

await Promise.all(paymentInfo.map(ln => (async () => {
        var payRef = ln.payment_ref
        var vendor = ln.vendor_id

        try {
            var finalPayment = await service.createPayment(args)
            console.log("Payment created")
        } catch (err) {
            // Log error to DB
            try {
                await service.dbUpdate(err)
                console.log("Error Logged to DB"))
            } catch (e) {}

           return
        }

       // Database update here with payment ID
})())

It may be unnecessary to have a continue statement if the only purpose was to react to the possibility of a payment not being created. In such case, you would simply use the payment value unconditionally, as any error thrown would skip the rest of the try block anyway!

await Promise.all(paymentInfo.map((async ln => {
        var payRef = ln.payment_ref
        var vendor = ln.vendor_id

        try {
            var finalPayment = await service.createPayment(args)
            console.log("Payment created")

            // Database update here with payment ID
        } catch (err) {
            // Log error to DB
            try {
                await service.dbUpdate(err)
                console.log("Error Logged to DB"))
            } catch (e) {}
        }
})())

Jumping over loop iteration following a JavaScript catch block

Answer №1

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