feat: cli script

cmd.js

@@ -0,0 +1,53 @@
+#!/usr/bin/env node
+
+import fs from 'fs';
+import {convertDocsHtmlToMarkdown} from './lib/convert.js';
+
+// to avoid top-level async/await. readFileSync(0) caused strange errors
+// https://stackoverflow.com/questions/67037353/any-way-to-read-from-stdin-synchronously-without-extra-modules-libraries-node-j
+function stdinReadSync() {
+    if (process.stdin.isTTY) {
+      return '';
+    }
+
+    const b = Buffer.alloc(1024)
+    let data = ''
+
+    while (true) {
+        let n = 0
+
+        // Read while EAGAIN
+        while (true) {
+            try {
+                n = fs.readSync(process.stdin.fd, b, 0, b.length)
+                break
+            } catch (e) {
+                if (e.code === 'EAGAIN') {
+                    // Sleep 100ms
+                    Atomics.wait(new Int32Array(new SharedArrayBuffer(4)), 0, 0, 100)
+                    continue
+                }
+                throw e
+            }
+        }
+
+        if (!n) break
+        data += b.toString('utf8', 0, n)
+    }
+
+    return data
+}
+
+// in order to debug this tool over the command line, you can read a file with broken input locally
+// ex: fs.readFileSync('./local-file.html', 'utf8');
+
+const inputHTML = stdinReadSync()
+
+if(!inputHTML) {
+  console.error('No input HTML provided. Please pipe HTML to this command.');
+  process.exit(1);
+}
+
+convertDocsHtmlToMarkdown(inputHTML).then(markdown => {
+  process.stdout.write(markdown);
+});