Here is my code that throws the exception. Not able to figure out why it says 'Unexpected reserved word'. main() function is an async type. It isn't plaining for above line of code.

const { BlobServiceClient } = require("@azure/storage-blob");
async function main() {
    try {
        const blobServiceClient = await BlobServiceClient.fromConnectionString('some string');
        let i = 1;
        const result = await blobServiceClient.listContainers();
        for await (const container of result) {
            console.log(`Container ${i++}: ${container.name}`);
        }
    } catch (error) {
        console.log(error);
    }
}

main();

Here is my code that throws the exception. Not able to figure out why it says 'Unexpected reserved word'. main() function is an async type. It isn't plaining for above line of code.

const { BlobServiceClient } = require("@azure/storage-blob");
async function main() {
    try {
        const blobServiceClient = await BlobServiceClient.fromConnectionString('some string');
        let i = 1;
        const result = await blobServiceClient.listContainers();
        for await (const container of result) {
            console.log(`Container ${i++}: ${container.name}`);
        }
    } catch (error) {
        console.log(error);
    }
}

main();

• javascript
• async-await
• azure-blob-storage

• 1 Probably the JavaScript engine does not support the for await syntax. Question is whether you really need it, since result is not an async iterable – trincot Commented Dec 4, 2019 at 20:34
• listContainer returns PagedAsyncIterableIterator<ContainerItem, ServiceListContainersSegmentResponse> object. This is the same code from the example for the blob-storage module, link: npmjs./package/@azure/storage-blob If you scroll down to the 'List the containers' section. – Taher Ghulam Mohammed Commented Dec 4, 2019 at 20:39

2 Answers 2

Your are getting this error because your Node version is lower than 10.0 and doesn't support for await...of. As a side note, for await has no effect here and can be substituted for just for Turns out api does need it

added: from the docs: you can either use for await of if your runtime supports it, or iterate an iterable in an old-fashioned way

let containerItem = await result.next();
while (!containerItem.done) {
  console.log(`Container ${i++}: ${containerItem.value.name}`);
  containerItem = await iter.next();
}

There is an work around for this one:

const { BlobServiceClient } = require("@azure/storage-blob");

async function main() {
    try {
        const blobServiceClient = await BlobServiceClient.fromConnectionString('DefaultEndpointsProtocol=https;AccountName=devappsstorage;AccountKey=aw/FF01OIfnYmK6Bh+d4NIhvVBaDKn942O22YAMNycX/27qKVwYW+/Dma/C7pI+lvU0wpo/VBJ1jFd4yi3MMWw==;EndpointSuffix=core.windows');
        let i = 1;
        let iter = blobServiceClient.listContainers();
        let containerItem = await iter.next();
        while (!containerItem.done) {
            console.log(`Container ${i++}: ${containerItem.value.name}`);
            containerItem = await iter.next();
          }
    } catch (error) {
        console.log(error);
    }
}

main();