How to use try, catch using async function with IIFE

1
votes

I am using async function with IIFE.
But when I run this code by rest api call,
it says

UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch().

I made try and catch inside of 'for loop'.
How can I make the correct try catch in this case? 

(async () => {
        for (let i = 0; i < keywordResult.places.length; i += 1) {
          try {
            const transformKeywordResult = await rp({
              method: 'GET',
              uri:
                '',
              qs: {
                query: query
              },
              json: true
            });

            let addrInfo = transformKeywordResult.addresses[i];
            if (!addrInfo.addressElements[8].longName) {
              addrInfo.addressElements[8].longName = '';
            }

            searchResult.push(transformKeywordResult);
          } catch (error) {
            return res.status(200).json({
              success: false,
              code: 500,
              msg: 'Internal Server Error',
              err: error,
              pos: 0
            });
          }
        }

        return res.send(searchResult);
      })();
2
javascriptnode.js
What exactly throws in that code? The await should be caught properly – CertainPerformance
Your query is the same in each loop iteration. Why not grab it once and iterate over the data instead? – Andy

2 Answers

0
votes

Try closing the for loop in the try block, because if any error occurs outside the try block, there is no catch block to hold the error. 

( async () => {

    try {
        for ( let i = 0; i < keywordResult.places.length; i += 1 ) {
            const transformKeywordResult = await rp( {
                method: 'GET',
                uri: '',
                qs: {
                    query: query
                },
                json: true
            } );

            let addrInfo = transformKeywordResult.addresses[ i ];
            if ( !addrInfo.addressElements[ 8 ].longName ) {
                addrInfo.addressElements[ 8 ].longName = '';
            }
            searchResult.push( transformKeywordResult );
        }
        return res.send( searchResult );
    } catch ( error ) {
        return res.status( 200 ).json( {
            success: false,
            code: 500,
            msg: 'Internal Server Error',
            err: error,
            pos: 0
        } );
    }

} )();
0
votes

Your rps are caught properly, but there's one promise left without apparent error catching, and that's your IIFE:

(async () => {
// do some stuff, including async
)();

It can, BTW, throw its own errors (independent of async API errors), for example when addrInfo.addressElements comes shorter than 9 elements long.

Try

(async () => {
// do some stuff, including async
)().catch(/* throw some error logic handling here, or even just noop */);