How to Sum an Array in JavaScript

Summing an array in JavaScript is a common task that can be accomplished in various ways. This guide will explore different methods to sum an array, providing detailed explanations and code examples for each approach.

let array = [1, 2, 3, 4, 5];
let sum = array.reduce((acc, curr) => acc + curr, 0);
console.log(sum); // 15

To sum an array in JavaScript, use the reduce() method:

Summing an array is a fundamental operation in JavaScript, often needed in various applications, from simple calculations to complex data manipulations. This guide will walk you through different methods to achieve this task, catering to different scenarios and preferences.

Using the reduce() Method

The reduce() method is a powerful and concise way to sum an array. It applies a function against an accumulator and each element in the array, reducing it to a single value.

Example 1: Basic Usage

let array = [1, 2, 3, 4, 5];
let sum = array.reduce((acc, curr) => acc + curr, 0);
console.log(sum); // 15

Explanation:

• array.reduce((acc, curr) => acc + curr, 0):
• acc is the accumulator, which stores the accumulated value.
• curr is the current element being processed.
• The function (acc, curr) => acc + curr adds each element to the accumulator.
• 0 is the initial value of the accumulator.
• The result, sum, is the total sum of the array elements.

Using a For Loop

A traditional for loop can also be used to sum an array. This method is straightforward and easy to understand.

Example 2: Using a For Loop

let array = [1, 2, 3, 4, 5];
let sum = 0;

for (let i = 0; i < array.length; i++) {
  sum += array[i];
}

console.log(sum); // 15

Explanation:

• let sum = 0; initializes the sum variable.
• The for loop iterates through each element of the array.
• sum += array[i]; adds the current element to the sum.
• The result, sum, is the total sum of the array elements.

Using the forEach() Method

The forEach() method executes a provided function once for each array element. It can also be used to sum the elements.

Example 3: Using the forEach() Method

let array = [1, 2, 3, 4, 5];
let sum = 0;

array.forEach(function(element) {
  sum += element;
});

console.log(sum); // 15

Explanation:

• let sum = 0; initializes the sum variable.
• array.forEach(function(element) { sum += element; });:
• element is the current element being processed.
• The function adds each element to the sum.
• The result, sum, is the total sum of the array elements.

Using Recursion

Recursion is a technique where a function calls itself. It can be used to sum an array, although it’s less common for this task.

Example 4: Using Recursion

let array = [1, 2, 3, 4, 5];

function sumArray(arr) {
  if (arr.length === 0) {
    return 0;
  } else {
    return arr[0] + sumArray(arr.slice(1));
  }
}

let sum = sumArray(array);
console.log(sum); // 15

Explanation:

• function sumArray(arr) { ... } defines a recursive function to sum an array.
• if (arr.length === 0) { return 0; } checks if the array is empty.
• return arr[0] + sumArray(arr.slice(1)); adds the first element to the sum of the remaining elements.
• let sum = sumArray(array); calls the function with the original array.
• The result, sum, is the total sum of the array elements.

Conclusion

Summing an array in JavaScript can be achieved using various methods, each with its advantages. Whether you prefer the concise reduce() method, the traditional for loop, the forEach() method, or even recursion, understanding these techniques will enhance your ability to manipulate arrays effectively.

By mastering these methods, you can handle array operations with confidence, making your JavaScript code more robust and efficient. Keep practicing and experimenting with different approaches to find the one that best suits your needs.