Document k6/experimental/fs module

docs/sources/next/javascript-api/k6-experimental/_index.md

@@ -1,19 +1,20 @@
 ---
-title: "k6/experimental"
-excerpt: "k6 experimental APIs"
+title: 'k6/experimental'
+excerpt: 'k6 experimental APIs'
 weight: 07
 ---
 
 # k6/experimental
 
 {{< docs/shared source="k6" lookup="experimental-module.md" version="<K6_VERSION>" >}}
 
-| Modules                                                                           | Description                                                                                                              |
-| --------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------ |
+| Modules                                                                                          | Description                                                                                                              |
+| ------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------ |
 | [browser](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/browser)       | Provides browser-level APIs to interact with browsers and collect frontend performance metrics as part of your k6 tests. |
 | [redis](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/redis)           | Functionality to interact with [Redis](https://redis.io/).                                                               |
 | [timers](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/timers)         | `setTimeout`, `clearTimeout`, `setInterval`, `clearInterval`                                                             |
 | [tracing](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/tracing)       | Support for instrumenting HTTP requests with tracing information.                                                        |
 | [webcrypto](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/webcrypto)   | Implements the [WebCrypto API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Crypto_API).                         |
 | [websockets](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/websockets) | Implements the browser's [WebSocket API](https://developer.mozilla.org/en-US/docs/Web/API/WebSocket).                    |
 | [grpc](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/grpc)             | Extends `k6/net/grpc` with the streaming capabilities.                                                                   |
+| [fs](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/fs)                 | Provides a memory-efficient way to handle file interactions within your test scripts.                                    |

docs/sources/next/javascript-api/k6-experimental/fs/FileInfo.md

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+---
+title: 'FileInfo'
+excerpt: 'FileInfo represents information about a file.'
+weight: 30
+---
+
+# FileInfo
+
+The `FileInfo` class represents information about a [file](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/fs/file).
+
+## Properties
+
+| Property | Type   | Description                    |
+| :------- | :----- | :----------------------------- |
+| name     | string | The name of the file.          |
+| size     | number | The size of the file in bytes. |
+
+## Example
+
+{{< code >}}
+
+```javascript
+import { open, SeekMode } from 'k6/experimental/fs';
+
+let file;
+(async function () {
+  file = await open('bonjour.txt');
+})();
+
+export default async function () {
+  // About information about the file
+  const fileinfo = await file.stat();
+  if (fileinfo.name != 'bonjour.txt') {
+    throw new Error('Unexpected file name');
+  }
+
+  const buffer = new Uint8Array(4);
+
+  let totalBytesRead = 0;
+  while (true) {
+    // Read into the buffer
+    const bytesRead = await file.read(buffer);
+    if (bytesRead == null) {
+      // EOF
+      break;
+    }
+
+    // Do something useful with the content of the buffer
+    totalBytesRead += bytesRead;
+
+    // If bytesRead is less than the buffer size, we've read the whole file
+    if (bytesRead < buffer.byteLength) {
+      break;
+    }
+  }
+
+  // Check that we read the expected number of bytes
+  if (totalBytesRead != fileinfo.size) {
+    throw new Error('Unexpected number of bytes read');
+  }
+
+  // Seek back to the beginning of the file
+  await file.seek(0, SeekMode.Start);
+}
+```
+
+{{< /code >}}

docs/sources/next/javascript-api/k6-experimental/fs/SeekMode.md

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+---
+title: 'SeekMode'
+excerpt: 'SeekMode is used to specify the position from which to seek in a file.'
+weight: 40
+---
+
+# SeekMode
+
+The `SeekMode` enum is used to specify the position from which to [seek](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/fs/file/seek) in a file.
+
+## Members
+
+| Member  | Value | Description                                 |
+| :------ | :---- | :------------------------------------------ |
+| Start   | 0     | Seek from the start of the file.            |
+| Current | 1     | Seek from the current position in the file. |
+| End     | 2     | Seek from the end of the file.              |
+
+## Example
+
+{{< code >}}
+
+```javascript
+import { open, SeekMode } from 'k6/experimental/fs';
+
+let file;
+(async function () {
+  file = await open('bonjour.txt');
+})();
+
+export default async function () {
+  // Seek 6 bytes from the start of the file
+  await file.seek(6, SeekMode.Start);
+
+  // Seek 2 more bytes from the current position
+  await file.seek(2, SeekMode.Current);
+
+  // Seek backwards 2 bytes from the end of the file
+  await file.seek(-2, SeekMode.End);
+}
+```
+
+{{< /code >}}

docs/sources/next/javascript-api/k6-experimental/fs/_index.md

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+---
+title: 'fs'
+excerpt: 'k6 fs experimental API'
+weight: 10
+---
+
+# fs
+
+{{< docs/shared source="k6" lookup="experimental-module.md" version="<K6_VERSION>" >}}
+
+The k6 filesystem experimental module provides a memory-efficient way to handle file interactions within your test scripts. It currently offers support for opening files, reading their content, and seeking through their content, and retrieving metadata about them.
+
+### Memory efficiency
+
+One of the key advantages of the filesystem module is its memory efficiency. Unlike the traditional [open]() function, which loads a file multiple times into memory, the filesystem module reduces memory usage by loading the file as little possible, and sharing the same memory space between all VUs. This approach signally reduces the memory footprint of your test script, and lets you load and process large files without running out of memory.
+
+### Notes on usage
+
+An important consideration when using the filesystem module is its handling of external file modifications. Once a file is loaded in k6, it behaves like a "view" over the content of the file. This means that if the underlying file is modified externally during a test, those changes won't be reflected in the loaded [File]() instance.
+
+## API Overview
+
+The module exports functions and objects to interact with the file system:
+
+| Function/Object                                                                                 | Description                                                                                          |
+| ----------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------- |
+| [open](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/fs/open)         | Opens a file and returns a promise resolving to a `File` instance.                                   |
+| [File](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/fs/file)         | Represents a file with methods for reading, seeking, and obtaining file stats.                       |
+| [SeekMode](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/fs/seekmode) | Enum for specifying the reference point for seek operations. Includes `Start`, `Current`, and `End`. |
+
+## Example
+
+{{< code >}}
+
+```javascript
+import { open, SeekMode } from 'k6/experimental/fs';
+
+// k6 doesn't support async in the init context. We use a top-level async function for `await`.
+//
+// Each Virtual User gets its own `file` copy.
+// So, operations like `seek` or `read` won't impact other VUs.
+let file;
+(async function () {
+  file = await open('bonjour.txt');
+})();
+
+export default async function () {
+  // About information about the file
+  const fileinfo = await file.stat();
+  if (fileinfo.name != 'bonjour.txt') {
+    throw new Error('Unexpected file name');
+  }
+
+  const buffer = new Uint8Array(4);
+
+  let totalBytesRead = 0;
+  while (true) {
+    // Read into the buffer
+    const bytesRead = await file.read(buffer);
+    if (bytesRead == null) {
+      // EOF
+      break;
+    }
+
+    // Do something useful with the content of the buffer
+    totalBytesRead += bytesRead;
+
+    // If bytesRead is less than the buffer size, we've read the whole file
+    if (bytesRead < buffer.byteLength) {
+      break;
+    }
+  }
+
+  // Check that we read the expected number of bytes
+  if (totalBytesRead != fileinfo.size) {
+    throw new Error('Unexpected number of bytes read');
+  }
+
+  // Seek back to the beginning of the file
+  await file.seek(0, SeekMode.Start);
+}
+```
+
+{{< /code >}}

docs/sources/next/javascript-api/k6-experimental/fs/file/_index.md

@@ -0,0 +1,75 @@
+---
+title: 'File'
+excerpt: 'File represents a file with methods for reading, seeking, and obtaining file stats.'
+weight: 10
+weight: 10
+---
+
+# File
+
+The `File` class represents a file with methods for reading, seeking, and obtaining file stats. It's returned by the [open](link-to-open-doc) function.
+
+## Properties
+
+| Property | Type   | Description                    |
+| :------- | :----- | :----------------------------- |
+| path     | string | The absolute path to the file. |
+
+## Methods
+
+| Method                                                                                       | Description                                                                                                                            |
+| :------------------------------------------------------------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------- |
+| [read](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/fs/file/read) | Reads up to `buffer.byteLength` bytes from the file into the passed `buffer`. Returns a promise resolving to the number of bytes read. |
+| [seek](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/fs/file/seek) | Sets the file position indicator for the file to the passed `offset` bytes. Returns a promise resolving to the new offset.             |
+| [stat](https://grafana.com/docs/k6/<K6_VERSION>/javascript-api/k6-experimental/fs/file/stat) | Returns a promise resolving to a [FileInfo](link-to-fileinfo-doc) object with information about the file.                              |
+
+## Example
+
+{{< code >}}
+
+```javascript
+import { open, SeekMode } from 'k6/experimental/fs';
+
+let file;
+(async function () {
+  file = await open('bonjour.txt');
+})();
+
+export default async function () {
+  // About information about the file
+  const fileinfo = await file.stat();
+  if (fileinfo.name != 'bonjour.txt') {
+    throw new Error('Unexpected file name');
+  }
+
+  const buffer = new Uint8Array(4);
+
+  let totalBytesRead = 0;
+  while (true) {
+    // Read into the buffer
+    const bytesRead = await file.read(buffer);
+    if (bytesRead == null) {
+      // EOF
+      break;
+    }
+
+    // Do something useful with the content of the buffer
+    totalBytesRead += bytesRead;
+
+    // If bytesRead is less than the buffer size, we've read the whole file
+    if (bytesRead < buffer.byteLength) {
+      break;
+    }
+  }
+
+  // Check that we read the expected number of bytes
+  if (totalBytesRead != fileinfo.size) {
+    throw new Error('Unexpected number of bytes read');
+  }
+
+  // Seek back to the beginning of the file
+  await file.seek(0, SeekMode.Start);
+}
+```
+
+{{< /code >}}

docs/sources/next/javascript-api/k6-experimental/fs/file/read.md

@@ -0,0 +1,72 @@
+---
+title: 'read'
+excerpt: 'the read method is used to read a chunk of the file.'
+weight: 20
+---
+
+# read
+
+The `read` method is used to read a chunk of the file into an [Uint8Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array) buffer.
+
+It resolves to either the number of bytes read during the operation, or `null` if there was nothing more to read.
+
+## Parameters
+
+| Parameter | Type                                                                                                      | Description                       |
+| :-------- | :-------------------------------------------------------------------------------------------------------- | :-------------------------------- |
+| buffer    | [Uint8Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array) | The buffer to read the data into. |
+
+## Returns
+
+A [Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) resolving to the number of bytes read or `null` if the end of the file has been reached.
+
+## Example
+
+{{< code >}}
+
+```javascript
+import { open, SeekMode } from 'k6/experimental/fs';
+
+let file;
+(async function () {
+  file = await open('bonjour.txt');
+})();
+
+export default async function () {
+  // About information about the file
+  const fileinfo = await file.stat();
+  if (fileinfo.name != 'bonjour.txt') {
+    throw new Error('Unexpected file name');
+  }
+
+  const buffer = new Uint8Array(4);
+
+  let totalBytesRead = 0;
+  while (true) {
+    // Read into the buffer
+    const bytesRead = await file.read(buffer);
+    if (bytesRead == null) {
+      // EOF
+      break;
+    }
+
+    // Do something useful with the content of the buffer
+    totalBytesRead += bytesRead;
+
+    // If bytesRead is less than the buffer size, we've read the whole file
+    if (bytesRead < buffer.byteLength) {
+      break;
+    }
+  }
+
+  // Check that we read the expected number of bytes
+  if (totalBytesRead != fileinfo.size) {
+    throw new Error('Unexpected number of bytes read');
+  }
+
+  // Seek back to the beginning of the file
+  await file.seek(0, SeekMode.Start);
+}
+```
+
+{{< /code >}}