Azure Storage Blob Ts

1---
2name: azure-storage-blob-ts
3description: |
4  Azure Blob Storage JavaScript/TypeScript SDK (@azure/storage-blob) for blob operations. Use for uploading, downloading, listing, and managing blobs and containers. Supports block blobs, append blobs, page blobs, SAS tokens, and streaming. Triggers: "blob storage", "@azure/storage-blob", "BlobServiceClient", "ContainerClient", "upload blob", "download blob", "SAS token", "block blob".
5package: "@azure/storage-blob"
6---
7 
8# @azure/storage-blob (TypeScript/JavaScript)
9 
10SDK for Azure Blob Storage operations — upload, download, list, and manage blobs and containers.
11 
12## Installation
13 
14```bash
15npm install @azure/storage-blob @azure/identity
16```
17 
18**Current Version**: 12.x  
19**Node.js**: >= 18.0.0
20 
21## Environment Variables
22 
23```bash
24AZURE_STORAGE_ACCOUNT_NAME=<account-name>
25AZURE_STORAGE_ACCOUNT_KEY=<account-key>
26# OR connection string
27AZURE_STORAGE_CONNECTION_STRING=DefaultEndpointsProtocol=https;AccountName=...
28```
29 
30## Authentication
31 
32### DefaultAzureCredential (Recommended)
33 
34```typescript
35import { BlobServiceClient } from "@azure/storage-blob";
36import { DefaultAzureCredential } from "@azure/identity";
37 
38const accountName = process.env.AZURE_STORAGE_ACCOUNT_NAME!;
39const client = new BlobServiceClient(
40  `https://${accountName}.blob.core.windows.net`,
41  new DefaultAzureCredential()
42);
43```
44 
45### Connection String
46 
47```typescript
48import { BlobServiceClient } from "@azure/storage-blob";
49 
50const client = BlobServiceClient.fromConnectionString(
51  process.env.AZURE_STORAGE_CONNECTION_STRING!
52);
53```
54 
55### StorageSharedKeyCredential (Node.js only)
56 
57```typescript
58import { BlobServiceClient, StorageSharedKeyCredential } from "@azure/storage-blob";
59 
60const accountName = process.env.AZURE_STORAGE_ACCOUNT_NAME!;
61const accountKey = process.env.AZURE_STORAGE_ACCOUNT_KEY!;
62 
63const sharedKeyCredential = new StorageSharedKeyCredential(accountName, accountKey);
64const client = new BlobServiceClient(
65  `https://${accountName}.blob.core.windows.net`,
66  sharedKeyCredential
67);
68```
69 
70### SAS Token
71 
72```typescript
73import { BlobServiceClient } from "@azure/storage-blob";
74 
75const accountName = process.env.AZURE_STORAGE_ACCOUNT_NAME!;
76const sasToken = process.env.AZURE_STORAGE_SAS_TOKEN!; // starts with "?"
77 
78const client = new BlobServiceClient(
79  `https://${accountName}.blob.core.windows.net${sasToken}`
80);
81```
82 
83## Client Hierarchy
84 
85```
86BlobServiceClient (account level)
87└── ContainerClient (container level)
88    └── BlobClient (blob level)
89        ├── BlockBlobClient (block blobs - most common)
90        ├── AppendBlobClient (append-only blobs)
91        └── PageBlobClient (page blobs - VHDs)
92```
93 
94## Container Operations
95 
96### Create Container
97 
98```typescript
99const containerClient = client.getContainerClient("my-container");
100await containerClient.create();
101 
102// Or create if not exists
103await containerClient.createIfNotExists();
104```
105 
106### List Containers
107 
108```typescript
109for await (const container of client.listContainers()) {
110  console.log(container.name);
111}
112 
113// With prefix filter
114for await (const container of client.listContainers({ prefix: "logs-" })) {
115  console.log(container.name);
116}
117```
118 
119### Delete Container
120 
121```typescript
122await containerClient.delete();
123// Or delete if exists
124await containerClient.deleteIfExists();
125```
126 
127## Blob Operations
128 
129### Upload Blob (Simple)
130 
131```typescript
132const containerClient = client.getContainerClient("my-container");
133const blockBlobClient = containerClient.getBlockBlobClient("my-file.txt");
134 
135// Upload string
136await blockBlobClient.upload("Hello, World!", 13);
137 
138// Upload Buffer
139const buffer = Buffer.from("Hello, World!");
140await blockBlobClient.upload(buffer, buffer.length);
141```
142 
143### Upload from File (Node.js only)
144 
145```typescript
146const blockBlobClient = containerClient.getBlockBlobClient("uploaded-file.txt");
147await blockBlobClient.uploadFile("/path/to/local/file.txt");
148```
149 
150### Upload from Stream (Node.js only)
151 
152```typescript
153import * as fs from "fs";
154 
155const blockBlobClient = containerClient.getBlockBlobClient("streamed-file.txt");
156const readStream = fs.createReadStream("/path/to/local/file.txt");
157 
158await blockBlobClient.uploadStream(readStream, 4 * 1024 * 1024, 5, {
159  // bufferSize: 4MB, maxConcurrency: 5
160  onProgress: (progress) => console.log(`Uploaded ${progress.loadedBytes} bytes`),
161});
162```
163 
164### Upload from Browser
165 
166```typescript
167const blockBlobClient = containerClient.getBlockBlobClient("browser-upload.txt");
168 
169// From File input
170const fileInput = document.getElementById("fileInput") as HTMLInputElement;
171const file = fileInput.files![0];
172await blockBlobClient.uploadData(file);
173 
174// From Blob/ArrayBuffer
175const arrayBuffer = new ArrayBuffer(1024);
176await blockBlobClient.uploadData(arrayBuffer);
177```
178 
179### Download Blob
180 
181```typescript
182const blobClient = containerClient.getBlobClient("my-file.txt");
183const downloadResponse = await blobClient.download();
184 
185// Read as string (browser & Node.js)
186const downloaded = await streamToText(downloadResponse.readableStreamBody!);
187 
188async function streamToText(readable: NodeJS.ReadableStream): Promise<string> {
189  const chunks: Buffer[] = [];
190  for await (const chunk of readable) {
191    chunks.push(Buffer.from(chunk));
192  }
193  return Buffer.concat(chunks).toString("utf-8");
194}
195```
196 
197### Download to File (Node.js only)
198 
199```typescript
200const blockBlobClient = containerClient.getBlockBlobClient("my-file.txt");
201await blockBlobClient.downloadToFile("/path/to/local/destination.txt");
202```
203 
204### Download to Buffer (Node.js only)
205 
206```typescript
207const blockBlobClient = containerClient.getBlockBlobClient("my-file.txt");
208const buffer = await blockBlobClient.downloadToBuffer();
209console.log(buffer.toString());
210```
211 
212### List Blobs
213 
214```typescript
215// List all blobs
216for await (const blob of containerClient.listBlobsFlat()) {
217  console.log(blob.name, blob.properties.contentLength);
218}
219 
220// List with prefix
221for await (const blob of containerClient.listBlobsFlat({ prefix: "logs/" })) {
222  console.log(blob.name);
223}
224 
225// List by hierarchy (virtual directories)
226for await (const item of containerClient.listBlobsByHierarchy("/")) {
227  if (item.kind === "prefix") {
228    console.log(`Directory: ${item.name}`);
229  } else {
230    console.log(`Blob: ${item.name}`);
231  }
232}
233```
234 
235### Delete Blob
236 
237```typescript
238const blobClient = containerClient.getBlobClient("my-file.txt");
239await blobClient.delete();
240 
241// Delete if exists
242await blobClient.deleteIfExists();
243 
244// Delete with snapshots
245await blobClient.delete({ deleteSnapshots: "include" });
246```
247 
248### Copy Blob
249 
250```typescript
251const sourceBlobClient = containerClient.getBlobClient("source.txt");
252const destBlobClient = containerClient.getBlobClient("destination.txt");
253 
254// Start copy operation
255const copyPoller = await destBlobClient.beginCopyFromURL(sourceBlobClient.url);
256await copyPoller.pollUntilDone();
257```
258 
259## Blob Properties & Metadata
260 
261### Get Properties
262 
263```typescript
264const blobClient = containerClient.getBlobClient("my-file.txt");
265const properties = await blobClient.getProperties();
266 
267console.log("Content-Type:", properties.contentType);
268console.log("Content-Length:", properties.contentLength);
269console.log("Last Modified:", properties.lastModified);
270console.log("ETag:", properties.etag);
271```
272 
273### Set Metadata
274 
275```typescript
276await blobClient.setMetadata({
277  author: "John Doe",
278  category: "documents",
279});
280```
281 
282### Set HTTP Headers
283 
284```typescript
285await blobClient.setHTTPHeaders({
286  blobContentType: "text/plain",
287  blobCacheControl: "max-age=3600",
288  blobContentDisposition: "attachment; filename=download.txt",
289});
290```
291 
292## SAS Token Generation (Node.js only)
293 
294### Generate Blob SAS
295 
296```typescript
297import {
298  BlobSASPermissions,
299  generateBlobSASQueryParameters,
300  StorageSharedKeyCredential,
301} from "@azure/storage-blob";
302 
303const sharedKeyCredential = new StorageSharedKeyCredential(accountName, accountKey);
304 
305const sasToken = generateBlobSASQueryParameters(
306  {
307    containerName: "my-container",
308    blobName: "my-file.txt",
309    permissions: BlobSASPermissions.parse("r"), // read only
310    startsOn: new Date(),
311    expiresOn: new Date(Date.now() + 3600 * 1000), // 1 hour
312  },
313  sharedKeyCredential
314).toString();
315 
316const sasUrl = `https://${accountName}.blob.core.windows.net/my-container/my-file.txt?${sasToken}`;
317```
318 
319### Generate Container SAS
320 
321```typescript
322import { ContainerSASPermissions, generateBlobSASQueryParameters } from "@azure/storage-blob";
323 
324const sasToken = generateBlobSASQueryParameters(
325  {
326    containerName: "my-container",
327    permissions: ContainerSASPermissions.parse("racwdl"), // read, add, create, write, delete, list
328    expiresOn: new Date(Date.now() + 24 * 3600 * 1000), // 24 hours
329  },
330  sharedKeyCredential
331).toString();
332```
333 
334### Generate Account SAS
335 
336```typescript
337import {
338  AccountSASPermissions,
339  AccountSASResourceTypes,
340  AccountSASServices,
341  generateAccountSASQueryParameters,
342} from "@azure/storage-blob";
343 
344const sasToken = generateAccountSASQueryParameters(
345  {
346    services: AccountSASServices.parse("b").toString(), // blob
347    resourceTypes: AccountSASResourceTypes.parse("sco").toString(), // service, container, object
348    permissions: AccountSASPermissions.parse("rwdlacupi"), // all permissions
349    expiresOn: new Date(Date.now() + 24 * 3600 * 1000),
350  },
351  sharedKeyCredential
352).toString();
353```
354 
355## Blob Types
356 
357### Block Blob (Default)
358 
359Most common type for text and binary files.
360 
361```typescript
362const blockBlobClient = containerClient.getBlockBlobClient("document.pdf");
363await blockBlobClient.uploadFile("/path/to/document.pdf");
364```
365 
366### Append Blob
367 
368Optimized for append operations (logs, audit trails).
369 
370```typescript
371const appendBlobClient = containerClient.getAppendBlobClient("app.log");
372 
373// Create the append blob
374await appendBlobClient.create();
375 
376// Append data
377await appendBlobClient.appendBlock("Log entry 1\n", 12);
378await appendBlobClient.appendBlock("Log entry 2\n", 12);
379```
380 
381### Page Blob
382 
383Fixed-size blobs for random read/write (VHDs).
384 
385```typescript
386const pageBlobClient = containerClient.getPageBlobClient("disk.vhd");
387 
388// Create 512-byte aligned page blob
389await pageBlobClient.create(1024 * 1024); // 1MB
390 
391// Write pages (must be 512-byte aligned)
392const buffer = Buffer.alloc(512);
393await pageBlobClient.uploadPages(buffer, 0, 512);
394```
395 
396## Error Handling
397 
398```typescript
399import { RestError } from "@azure/storage-blob";
400 
401try {
402  await containerClient.create();
403} catch (error) {
404  if (error instanceof RestError) {
405    switch (error.statusCode) {
406      case 404:
407        console.log("Container not found");
408        break;
409      case 409:
410        console.log("Container already exists");
411        break;
412      case 403:
413        console.log("Access denied");
414        break;
415      default:
416        console.error(`Storage error ${error.statusCode}: ${error.message}`);
417    }
418  }
419  throw error;
420}
421```
422 
423## TypeScript Types Reference
424 
425```typescript
426import {
427  // Clients
428  BlobServiceClient,
429  ContainerClient,
430  BlobClient,
431  BlockBlobClient,
432  AppendBlobClient,
433  PageBlobClient,
434 
435  // Authentication
436  StorageSharedKeyCredential,
437  AnonymousCredential,
438 
439  // SAS
440  BlobSASPermissions,
441  ContainerSASPermissions,
442  AccountSASPermissions,
443  AccountSASServices,
444  AccountSASResourceTypes,
445  generateBlobSASQueryParameters,
446  generateAccountSASQueryParameters,
447 
448  // Options & Responses
449  BlobDownloadResponseParsed,
450  BlobUploadCommonResponse,
451  ContainerCreateResponse,
452  BlobItem,
453  ContainerItem,
454 
455  // Errors
456  RestError,
457} from "@azure/storage-blob";
458```
459 
460## Best Practices
461 
4621. **Use DefaultAzureCredential** — Prefer AAD over connection strings/keys
4632. **Use streaming for large files** — `uploadStream`/`downloadToFile` for files > 256MB
4643. **Set appropriate content types** — Use `setHTTPHeaders` for correct MIME types
4654. **Use SAS tokens for client access** — Generate short-lived tokens for browser uploads
4665. **Handle errors gracefully** — Check `RestError.statusCode` for specific handling
4676. **Use `*IfNotExists` methods** — For idempotent container/blob creation
4687. **Close clients** — Not required but good practice in long-running apps
469 
470## Platform Differences
471 
472| Feature | Node.js | Browser |
473|---------|---------|---------|
474| `StorageSharedKeyCredential` | ✅ | ❌ |
475| `uploadFile()` | ✅ | ❌ |
476| `uploadStream()` | ✅ | ❌ |
477| `downloadToFile()` | ✅ | ❌ |
478| `downloadToBuffer()` | ✅ | ❌ |
479| `uploadData()` | ✅ | ✅ |
480| SAS generation | ✅ | ❌ |
481| DefaultAzureCredential | ✅ | ❌ |
482| Anonymous/SAS access | ✅ | ✅ |
483