Add 2-read_file.js file

Author: Mar-Issah

0x05-Node_JS_basic/1-stdin.js

@@ -2,11 +2,11 @@ process.stdin.setEncoding('utf8');
 
 console.log('Welcome to Holberton School, what is your name?');
 
-process.stdin.on('data', (input) => {
-  const name = input.trim();
+process.stdin.on('readable', () => {
+  const name = process.stdin.read();
 
   if (name.length > 0) {
-    console.log(`Your name is: ${input}`);
+    process.stdout.write(`Your name is: ${name}`);
     process.exit();
   }
 });

0x05-Node_JS_basic/2-read_file.js

@@ -0,0 +1,49 @@
+const fs = require('fs');
+
+/**
+ * Counts the students in a CSV data file.
+ * @param {String} path The path to the CSV data file.
+ * @returns {void}
+ */
+
+function countStudents(path) {
+  try {
+    const data = fs.readFileSync(path, 'utf8').split('\n');
+
+    if (data.length === 0) {
+      throw new Error('Cannot load the database');
+    }
+    const students = data.map((line) => line.split(','));
+
+    console.log(`Number of students: ${students.length - 1}`);
+
+    const fields = students[0];
+    const fieldIndex = fields.indexOf('field');
+
+    if (fieldIndex === -1) {
+      throw new Error('Field column not found');
+    }
+
+    const validStudents = students
+      .slice(1)
+      .filter((student) => student[fieldIndex] !== undefined && student[fieldIndex] !== '');
+
+    const classes = validStudents.reduce((acc, student) => {
+      const className = student[fieldIndex];
+      if (!acc[className]) {
+        acc[className] = [];
+      }
+      acc[className].push(student[fields.indexOf('firstname')]);
+      return acc;
+    }, {});
+
+    for (const [className, studentList] of Object.entries(classes)) {
+      console.log(`Number of students in ${className}: ${studentList.length}. List: ${studentList.join(', ')}`);
+    }
+  } catch (error) {
+    console.error(error.message);
+  }
+}
+
+countStudents('database.csv');
+module.exports = countStudents;

0x05-Node_JS_basic/3-read_file_async.js

@@ -0,0 +1,49 @@
+const fs = require('fs');
+
+/**
+ * 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>
+ */
+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);
+
+      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)
+        .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);
+    }
+  });
+});
+
+module.exports = countStudents;