complete cat excercise

Author: enjoy15

implement-shell-tools/cat/cat.js

@@ -0,0 +1,60 @@
+#!/usr/bin/env node
+
+const fs = require('fs');
+const path = require('path');
+
+function cat(files, options) {
+  let lineNumber = 1;
+
+  files.forEach((file) => {
+    const filePath = path.resolve(file);
+
+    try {
+      const data = fs.readFileSync(filePath, 'utf8');
+      const lines = data.split('\n');
+
+      lines.forEach((line) => {
+        if (options.numberNonEmpty && line.trim()) {
+          console.log(`${lineNumber}\t${line}`);
+          lineNumber++;
+        } else if (options.numberLines) {
+          console.log(`${lineNumber}\t${line}`);
+          lineNumber++;
+        } else {
+          console.log(line);
+        }
+      });
+    } catch (err) {
+      console.error(`cat: ${file}: No such file or directory`);
+    }
+  });
+}
+
+function main() {
+  const args = process.argv.slice(2);
+  const options = {
+    numberLines: false,
+    numberNonEmpty: false,
+  };
+
+  const files = [];
+
+  args.forEach((arg) => {
+    if (arg === '-n') {
+      options.numberLines = true;
+    } else if (arg === '-b') {
+      options.numberNonEmpty = true;
+    } else {
+      files.push(arg);
+    }
+  });
+
+  if (files.length === 0) {
+    console.error('Usage: node cat.js [-n | -b] <file>...');
+    process.exit(1);
+  }
+
+  cat(files, options);
+}
+
+main();