JavaScript: Explain why the the await operator in a function declaration is the same in a function invocation?

Consider the following I have a call to DynamoDB using this function declaration:

async putItem(param: DynamoDB.DocumentClient.PutItemInput): Promise<void> {
	await this.dynamoDb.getDynamoDBDocClient().put(param).promise();
}

In a service I am using it like this:

try {
    await this.dsDynamoDBService.updateItem({
        TableName: this.dsConfig.aws.dynamoDB.table,
        Key: {
            id: docGenReq.id,
            type: EItemType.REQUEST
        },
        UpdateExpression: 'set requestStatus = :requestStatus, requestErrored = :requestErrored',
        ExpressionAttributeValues: {
            ':requestStatus': EDSRequestRequestDetails.COMPLETE,
            ':requestErrored': false
        }
    });
} catch (error) {
    this.logService.error(error);
}

Is the await in the try catch even necessary? If so why?

> Is the await in the try catch even necessary? If so why?

Yes, if you want that try/catch to handle rejections. If you didn't have the await, your code wouldn't be doing anything with the promise that this.dsDynamoDBService.updateItem returns, which means two things:

1. Your code carries on before the promise is settled, and

2. Your try/catch won't catch it if the promise is rejected

In contrast, with the await, your code waits for the promise to settle, and if that settlement is a rejection, it passes that rejection to the catch block.

Also note that if you didn't have the await, based on the code shown, nothing would be handling the promise rejection (if one occurred), leading to an unhandled rejection, which is just like an unhandled error. If this code were running in Node.js or Deno, for instance, that might terminate the process.