Answer

data/grades.js

@@ -0,0 +1,34 @@
+grades = [{
+    assignmentName: 'Assignment01',
+    studentName: 'Timmy',
+    score: 90
+},
+{
+    assignmentName: 'Assignment01',
+    studentName: 'Zoey',
+    score: 95
+},
+{
+    assignmentName: 'Assignment02',
+    studentName: 'Timmy',
+    score: 85
+},
+{
+    assignmentName: 'Assignment02',
+    studentName: 'Zoey',
+    score: 70
+},
+{
+    assignmentName: 'Assignment03',
+    studentName: 'Zoey',
+    score: 100
+},
+{
+    assignmentName: 'Assignment03',
+    studentName: 'Timmy',
+    score: 60
+}]
+
+module.exports = {
+    grades
+}

index.js

@@ -29,25 +29,72 @@
             - Use 2 distinct student names
 
  */
+const { grades } = require('./data/grades')
 
- /**
+// console.log({ grades })
+/**
 
-    Looping using your preferred looping syntax and updating a shared variable
+   Looping using your preferred looping syntax and updating a shared variable
 
-    2) Loop through the grades data using a for loop.
-        Update `gradeTotal` so it increases value for each item in the array
+   2) Loop through the grades data using a for loop.
+       Update `gradeTotal` so it increases value for each item in the array
 
- */
- const gradeTotal = 0
+*/
+// expect gradeTotal = 500
+function totalGrades(grades) {
+    let gradeTotal = 0
+    grades.forEach((grade) => {
+        const { score } = grade
+        gradeTotal += score
+    })
+    return gradeTotal
+}
+
+console.log(totalGrades(grades))
+
+// add in for...in loop option 1
+gradeTotal = 0
+
+for (const index in grades) {
+    const { score } = grades[index]
+    console.log({ score })
+    gradeTotal += score
+}
+console.log({ gradeTotal })
 
+gradeTotal = 0
 
- /**
+for (const index in grades) {
+    const grade = grades[index]
+    gradeTotal += grade.score
+}
+console.log({ gradeTotal })
+/**
 
-    Using reduce
+   Using reduce
 
-    3) Use Array reduce to do the same total calculation logic
+   3) Use Array reduce to do the same total calculation logic
 
-        Replace `null` below with the use of `reduce`
+       Replace `null` below with the use of `reduce`
 
-  */
-  gradeTotal = null
+ */
+function totalGrades(grades) {
+    const gradeTotal = grades.reduce((total, grade) => {
+        console.log(total, grade)
+        return total + grade.score
+    }, 0)
+    return gradeTotal
+}
+
+console.log(totalGrades(grades))
+
+function totalGradesAlt(grades) {
+    const gradeTotal = grades.reduce((total, grade) => {
+        console.log(total, grade)
+        const { score } = grade
+        return total + score
+    }, 0)
+    return gradeTotal
+}
+
+console.log(totalGradesAlt(grades))