CODEWITHSUNDEEP
javascriptnode.jsasynchronousaws-lambda
incnnu
incnnu

Reputation: 193

Why is this Lambda function async?

This Lambda function does an http-request and then writes the data into DynamoDB. I'm wondering why the function is set asynchronously. Wouldn't it be the same if it weren't async? As far as I know, await tells the code to pause and to continue after httprequest() is done. Isn't that the same like running the code synchronously?

exports.handler = async (event) => {
    try {
        const data = await httprequest();

        for (var i = 0; i < data.d.results.length; i++){
            var iden = Date.now();
            var identifier = iden.toString();
            datestring.substring(4,6) + "-" + datestring.substring(6,8);
            
        //add to dynamodb
        var params = {
            Item: {
                id: identifier,
                date: data.d.results[i].DAY_T,
            },
        TableName: 'DB'
        };
        await docClient.put(params).promise();
        }
        
        console.log('Document inserted.');
        return JSON.stringify(data);
    } catch(err) {
        console.log(err);
        return err;
    }
};

Upvotes: 0

Views: 99

Answers (1)

Jamiec
Jamiec

Reputation: 136164

async/await is syntactic sugar which makes writing code look similarly to how synchronous code would be written while maintaining all of the advantages of asynchronous code.

Essentially this:

var result = await doSomethingAsync();
console.log(result);

is actually this:

doSomethingAsync().then(result => {
    console.log(result);
});

If you imagine doing lots of this it gets heavily nested very quickly. When you include error handling too, the then/catch method gets long and verbose. async/await lets you use try/catch in a more natural way - the same way you're used to for synchronous code.

Mix in the fact that your code is doing multiple await within a loop, and I'd need to build up a list of promises and do a Promise.all there too. It all gets pretty hard to write without making a mistake.

Upvotes: 1

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