The JavaScript rest operator, denoted by three dots (

In summary, the rest operator (

 


// Example 1: Gathering remaining arguments into an array
function printTeachers(firstTeacher, secondTeacher, ...otherTeachers) {
  console.log(`First Teacher: ${firstTeacher}`);
  console.log(`Second Teacher: ${secondTeacher}`);
  console.log(`Other Teachers: ${otherTeachers.join(', ')}`);
}


 
let teachers = ['Alice', 'Bob', 'Charlie', 'David'];
printTeachers(...teachers);
// Output:
// First Teacher: Alice
// Second Teacher: Bob
// Other Teachers: Charlie, David

// Example 2: Combining arrays
let moreTeachers = ['Eve', 'Frank'];
let allTeachers = [...teachers, ...moreTeachers];
console.log(allTeachers);
// Output: ['Alice', 'Bob', 'Charlie', 'David', 'Eve', 'Frank']

// Example 3: Copying an array
let copiedTeachers = [...teachers];
console.log(copiedTeachers);
// Output: ['Alice', 'Bob', 'Charlie', 'David']

// Example 4: Finding the maximum value in an array
let scores = [85, 92, 78, 90];
let maxScore = Math.max(...scores);
console.log(maxScore);
// Output: 92

// Example 5: Using rest parameters in a function
function calculateAverage(...scores) {
  let total = scores.reduce((sum, score) => sum + score, 0);
  return total / scores.length;
}

let averageScore = calculateAverage(85, 92, 78, 90);
console.log(averageScore);
// Output: 86.25

 

Explanation:

1. Example 1: The function

   printTeachers
   printTeachers takes two specific teachers as arguments (
   firstTeacher
   firstTeacher and
   secondTeacher
   secondTeacher) and uses the rest parameter
   ...otherTeachers
   ...otherTeachers to collect any additional teachers. This allows us to pass an arbitrary number of teachers to the function.

2. Example 2: The spread operator (

   ...
   ...) is used to merge two arrays (
   teachers
   teachers and
   moreTeachers
   moreTeachers) into a single array (
   allTeachers
   allTeachers).

3. Example 3: The spread operator is used to create a copy of the

   teachers
   teachers array. This is useful if you want to make changes to a copy without affecting the original array.

4. Example 4: The spread operator is used to pass the elements of the

   scores
   scores array as separate arguments to the
   Math.max
   Math.max function. This allows us to find the maximum value in the array.

5. Example 5: The function

   calculateAverage
   calculateAverage uses a rest parameter (
   ...scores
   ...scores) to accept an arbitrary number of scores. The function then calculates the average of these scores.