Optionally depend on node:fs

CHANGES.md

@@ -8,8 +8,11 @@ Version 0.4.2
 
 To be released.
 
- -  The npm version of LogTape no more depends on `node:stream/web` module.
-    This should make it easier to use LogTape on edge functions.
+ -  LogTape now works well on edge functions.
+
+     -  The npm version of LogTape no more depends on `node:stream/web` module.
+     -  LogTape now works well with JavaScript runtimes that do not support
+        `node:fs` module.
 
 
 Version 0.4.1

dnt.ts

@@ -31,6 +31,7 @@ await build({
   mappings: {
     "./logtape/filesink.jsr.ts": "./logtape/filesink.node.ts",
     "./logtape/filesink.deno.ts": "./logtape/filesink.node.ts",
+    "./logtape/fs.ts": "./logtape/fs.js",
   },
   shims: {
     deno: "dev",
@@ -42,6 +43,8 @@ await build({
     lib: ["ES2021", "DOM"],
   },
   async postBuild() {
+    await Deno.copyFile("logtape/fs.mjs", "npm/esm/fs.js");
+    await Deno.copyFile("logtape/fs.cjs", "npm/script/fs.js");
     await Deno.copyFile("LICENSE", "npm/LICENSE");
     await Deno.copyFile("README.md", "npm/README.md");
   },

logtape/filesink.node.ts

@@ -1,4 +1,6 @@
-import fs from "node:fs";
+// @ts-ignore: a trick to avoid module resolution error on non-Node.js environ
+import fsMod from "./fs.ts";
+import type fsType from "node:fs";
 import { webDriver } from "./filesink.web.ts";
 import {
   type FileSinkOptions,
@@ -9,19 +11,24 @@ import {
   type Sink,
 } from "./sink.ts";
 
+// @ts-ignore: a trick to avoid module resolution error on non-Node.js environ
+const fs = fsMod as (typeof fsType | null);
+
 /**
  * A Node.js-specific file sink driver.
  */
-export const nodeDriver: RotatingFileSinkDriver<number> = {
-  openSync(path: string) {
-    return fs.openSync(path, "a");
-  },
-  writeSync: fs.writeSync,
-  flushSync: fs.fsyncSync,
-  closeSync: fs.closeSync,
-  statSync: fs.statSync,
-  renameSync: fs.renameSync,
-};
+export const nodeDriver: RotatingFileSinkDriver<number | void> = fs == null
+  ? webDriver
+  : {
+    openSync(path: string) {
+      return fs.openSync(path, "a");
+    },
+    writeSync: fs.writeSync,
+    flushSync: fs.fsyncSync,
+    closeSync: fs.closeSync,
+    statSync: fs.statSync,
+    renameSync: fs.renameSync,
+  };
 
 /**
  * Get a file sink.

logtape/fs.cjs

@@ -0,0 +1,8 @@
+let fs;
+try {
+  fs = require("node:fs");
+} catch (_) {
+  fs = null;
+}
+
+module.exports = fs;

logtape/fs.js

@@ -0,0 +1 @@
+export * from "node:fs";

logtape/fs.mjs

@@ -0,0 +1,12 @@
+let fs;
+try {
+  fs = await import("node:fs");
+} catch (e) {
+  if (e instanceof TypeError) {
+    fs = null;
+  } else {
+    throw e;
+  }
+}
+
+export default fs;

logtape/fs.ts

@@ -0,0 +1,12 @@
+let fs;
+try {
+  fs = await import("node:fs");
+} catch (e) {
+  if (e instanceof TypeError) {
+    fs = null;
+  } else {
+    throw e;
+  }
+}
+
+export default fs;