refactor: use async API

Author: snitin315

lib/Server.js

@@ -545,11 +545,14 @@ class Server {
       if (!options.https.key || !options.https.cert) {
         const certificateDir = Server.findCacheDir();
         const certificatePath = path.join(certificateDir, "server.pem");
-        let certificateExists = fs.existsSync(certificatePath);
+        let certificateExists = await fs.promises.access(
+          certificatePath,
+          fs.constants.F_OK
+        );
 
         if (certificateExists) {
           const certificateTtl = 1000 * 60 * 60 * 24;
-          const certificateStat = fs.statSync(certificatePath);
+          const certificateStat = await fs.promises.stat(certificatePath);
 
           const now = new Date();
 
@@ -634,34 +637,18 @@ class Server {
             ],
           });
 
-          await fs.mkdir(certificateDir, { recursive: true }, (error) => {
-            if (error) {
-              this.logger.error(error);
-            }
-          });
+          await fs.promises.mkdir(certificateDir, { recursive: true });
 
-          await fs.writeFile(
+          await fs.promises.writeFile(
             certificatePath,
             pems.private + pems.cert,
             {
               encoding: "utf8",
-            },
-            (error) => {
-              if (error) {
-                this.logger.error(error);
-              }
             }
           );
         }
 
-        fakeCert = await new Promise((resolve, reject) => {
-          fs.readFile(certificatePath, (error, data) => {
-            if (error) {
-              reject(error);
-            }
-            resolve(data);
-          });
-        });
+        fakeCert = await fs.promises.readFile(certificatePath);
 
         this.logger.info(`SSL certificate: ${certificatePath}`);
       }
@@ -1179,7 +1166,7 @@ class Server {
     app.get("/__webpack_dev_server__/sockjs.bundle.js", (req, res) => {
       res.setHeader("Content-Type", "application/javascript");
 
-      const { createReadStream } = require("graceful-fs");
+      const { createReadStream } = fs;
       const clientPath = path.join(__dirname, "..", "client");
 
       createReadStream(
@@ -2054,10 +2041,10 @@ class Server {
         const net = require("net");
         const socket = new net.Socket();
 
-        socket.on("error", (error) => {
+        socket.on("error", async (error) => {
           if (error.code === "ECONNREFUSED") {
             // No other server listening on this socket so it can be safely removed
-            fs.unlinkSync(this.options.ipc);
+            await fs.promises.unlink(this.options.ipc);
 
             resolve();
 
@@ -2096,11 +2083,7 @@ class Server {
       // chmod 666 (rw rw rw)
       const READ_WRITE = 438;
 
-      await fs.chmod(this.options.ipc, READ_WRITE, (error) => {
-        if (error) {
-          this.logger.error(error);
-        }
-      });
+      await fs.promises.chmod(this.options.ipc, READ_WRITE);
     }
 
     if (this.options.webSocketServer) {