Add 3-read_file_async.js file

Author: Mar-Issah

0x05-Node_JS_basic/1-stdin.js

@@ -1,6 +1,4 @@
-process.stdin.setEncoding('utf8');
-
-console.log('Welcome to Holberton School, what is your name?');
+process.stdout.write('Welcome to Holberton School, what is your name?\n');
 
 process.stdin.on('readable', () => {
   const name = process.stdin.read();

0x05-Node_JS_basic/2-read_file.js

@@ -15,7 +15,7 @@ function countStudents(path) {
     }
     const students = data.map((line) => line.split(','));
 
-    console.log(`Number of students: ${students.length - 1}`);
+    console.log(`Number of students: ${students.slice(1).length - 1}`);
 
     const fields = students[0];
     const fieldIndex = fields.indexOf('field');

0x05-Node_JS_basic/3-read_file_async.js

@@ -1,49 +1,39 @@
-const fs = require('fs');
+const fs = require('fs/promises');
 
 /**
  * Counts the students in a CSV data file.
- * @param {String} dataPath The path to the CSV data file.
- * @author Bezaleel Olakunori <https://github.com/B3zaleel>
+ * @param {String} path - The path to the CSV data file.
+ * @returns {Promise<void>}
  */
-const countStudents = (dataPath) => new Promise((resolve, reject) => {
-  fs.readFile(dataPath, 'utf-8', (err, data) => {
-    if (err) {
-      reject(new Error('Cannot load the database'));
-    }
-    if (data) {
-      const fileLines = data
-        .toString('utf-8')
-        .trim()
-        .split('\n');
-      const studentGroups = {};
-      const dbFieldNames = fileLines[0].split(',');
-      const studentPropNames = dbFieldNames
-        .slice(0, dbFieldNames.length - 1);
+const countStudents = async (path) => {
+  try {
+    const data = await fs.readFile(path, 'utf-8');
+    const fileLines = data.trim().split('\n');
+    const studentGroups = {};
+    const dbFieldNames = fileLines[0].split(',');
+    const studentPropNames = dbFieldNames.slice(0, -1);
+
+    fileLines.slice(1).forEach((line) => {
+      const [field, ...studentPropValues] = line.split(',');
+      studentGroups[field] = [
+        ...(studentGroups[field] || []),
+        Object.fromEntries(studentPropNames.map((propName, idx) => [propName, studentPropValues[idx]])),
+      ];
+    });
 
-      for (const line of fileLines.slice(1)) {
-        const studentRecord = line.split(',');
-        const studentPropValues = studentRecord
-          .slice(0, studentRecord.length - 1);
-        const field = studentRecord[studentRecord.length - 1];
-        if (!Object.keys(studentGroups).includes(field)) {
-          studentGroups[field] = [];
-        }
-        const studentEntries = studentPropNames
-          .map((propName, idx) => [propName, studentPropValues[idx]]);
-        studentGroups[field].push(Object.fromEntries(studentEntries));
-      }
+    const totalStudents = Object.values(studentGroups).flat().length;
+    console.log(`Number of students: ${totalStudents}`);
 
-      const totalStudents = Object
-        .values(studentGroups)
-        .reduce((pre, cur) => (pre || []).length + cur.length);
-      console.log(`Number of students: ${totalStudents}`);
-      for (const [field, group] of Object.entries(studentGroups)) {
-        const studentNames = group.map((student) => student.firstname).join(', ');
-        console.log(`Number of students in ${field}: ${group.length}. List: ${studentNames}`);
-      }
-      resolve(true);
+    for (const [field, group] of Object.entries(studentGroups)) {
+      const studentNames = group.map((student) => student.firstname).join(', ');
+      console.log(`Number of students in ${field}: ${group.length}. List: ${studentNames}`);
     }
-  });
-});
+
+    return true;
+  } catch (error) {
+    console.error('Cannot load the database');
+    throw error;
+  }
+};
 
 module.exports = countStudents;