Create async-event-emitter.js

Author: varun93

async-event-emitter.js

@@ -0,0 +1,46 @@
+const EventEmitter = require("events");
+const fs = require("fs");
+const promisify = require("./promisify");
+
+class WithTime extends EventEmitter {
+  async execute(asyncFunc, ...args) {
+    this.emit("begin");
+    try {
+      console.time("execute");
+      const data = await asyncFunc(...args);
+      this.emit("data", data);
+      console.timeEnd("execute");
+      this.emit("end");
+    } catch (err) {
+      this.emit("error", err);
+    }
+  }
+}
+
+const readFileAsArray = async file => {
+  try {
+    const readFile = promisify(fs.readFile);
+    const data = await readFile([file]);
+    const lines = data
+      .toString()
+      .trim()
+      .split("\n");
+    return lines;
+  } catch (error) {
+    throw new Error(error);
+  }
+};
+
+const withTime = new WithTime();
+
+withTime.on("begin", () => console.log("About to execute"));
+withTime.on("end", () => console.log("Done with execute"));
+withTime.on("data", data => {
+  console.log(data);
+});
+withTime.on("error", error => {
+  console.log(error);
+});
+
+const filename = "test.txt";
+withTime.execute(readFileAsArray, filename);