feat(wc): implement basic word count utility

- Add wc/wc.js: reads files and outputs line, word, and byte counts
- Support multiple files with totals row
- Use fs.promises.readFile for async file reading
- Add error handling for missing files with non-zero exit code
- Format output to match standard wc utility (padded columns)
- docs(wc): normalize README bullets so example commands render correctly

Author: Iswanna

implement-shell-tools/wc/README.md

@@ -6,11 +6,11 @@ Your task is to implement your own version of `wc`.
 
 It must act the same as `wc` would, if run from the directory containing this README.md file, for the following command lines:
 
-* `wc sample-files/*`
-* `wc -l sample-files/3.txt`
-* `wc -w sample-files/3.txt`
-* `wc -c sample-files/3.txt`
-* `wc -l sample-files/*`
+- `wc sample-files/*`
+- `wc -l sample-files/3.txt`
+- `wc -w sample-files/3.txt`
+- `wc -c sample-files/3.txt`
+- `wc -l sample-files/*`
 
 Matching any additional behaviours or flags are optional stretch goals.
 

implement-shell-tools/wc/wc.js

@@ -0,0 +1,67 @@
+import process from "node:process";
+import { promises as fs } from "node:fs";
+
+/**
+ * Calculates the lines, words, and bytes for a given file.
+ */
+async function calculateFileStats(filePath) {
+  const fileBuffer = await fs.readFile(filePath);
+  const fileContent = fileBuffer.toString();
+
+  // Standard 'wc' counts newline characters (\n)
+  const lineCount = fileContent.split("\n").length - 1;
+
+  // Split by any whitespace and filter out empty strings to get actual words
+  const wordCount = fileContent
+    .split(/\s+/)
+    .filter((word) => word.length > 0).length;
+
+  // Buffer.length provides the exact byte count on disk
+  const byteCount = fileBuffer.length;
+
+  return { lineCount, wordCount, byteCount, filePath };
+}
+
+/**
+ * Main execution function
+ */
+async function runWordCount() {
+  const filePaths = process.argv.slice(2);
+  const results = [];
+
+  for (const filePath of filePaths) {
+    try {
+      const stats = await calculateFileStats(filePath);
+      results.push(stats);
+
+      printFormattedLine(
+        stats.lineCount,
+        stats.wordCount,
+        stats.byteCount,
+        stats.filePath,
+      );
+    } catch (error) {
+      console.error(`wc: ${filePath}: No such file or directory`);
+      process.exitCode = 1;
+    }
+  }
+
+  // If multiple files were processed, show the total
+  if (results.length > 1) {
+    const totalLines = results.reduce((sum, item) => sum + item.lineCount, 0);
+    const totalWords = results.reduce((sum, item) => sum + item.wordCount, 0);
+    const totalBytes = results.reduce((sum, item) => sum + item.byteCount, 0);
+
+    printFormattedLine(totalLines, totalWords, totalBytes, "total");
+  }
+}
+
+/**
+ * Formats the output into columns to match the standard 'wc' utility
+ */
+function printFormattedLine(lines, words, bytes, label) {
+  const format = (number) => String(number).padStart(8);
+  console.log(`${format(lines)}${format(words)}${format(bytes)} ${label}`);
+}
+
+runWordCount();