implement wc

Author: pathywang

implement-shell-tools/wc/wc.js

@@ -0,0 +1,57 @@
+const fs = require("fs");
+
+const args = process.argv.slice(2);
+
+let countLines = false;
+let countWords = false;
+let countBytes = false;
+let files = [];
+
+for (const arg of args) {
+    if (arg === "-l") {
+        countLines = true;
+    } else if (arg === "-w") {
+        countWords = true;
+    } else if (arg === "-c") {
+        countBytes = true;
+    } else {
+        files.push(arg);
+    }
+}
+
+// If no flags are given, wc shows all three
+if (!countLines && !countWords && !countBytes) {
+    countLines = true;
+    countWords = true;
+    countBytes = true;
+}
+
+function countFile(filename) {
+    const content = fs.readFileSync(filename, "utf8");
+
+    const lines = content.split("\n").length - 1;
+    const words = content.trim() === "" ? 0 : content.trim().split(/\s+/).length;
+    const bytes = Buffer.byteLength(content);
+
+    let output = [];
+
+    if (countLines) {
+        output.push(lines);
+    }
+
+    if (countWords) {
+        output.push(words);
+    }
+
+    if (countBytes) {
+        output.push(bytes);
+    }
+
+    output.push(filename);
+
+    console.log(output.join(" "));
+}
+
+for (const file of files) {
+    countFile(file);
+}