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# How to find the sum of all elements of a given array in JavaScript?

In programming, it is often necessary to find the sum of all elements in an array. There are many ways to do this in JavaScript. In this tutorial, we are going to look at some of the ways to find the sum of all elements in an array.

## Using the for loop

Finding the sum of all elements in an array is a very common operation in JavaScript, and the **for loop** is the easiest way to do it. If you are working with arrays in JavaScript, make sure to take advantage of the for loop to find the sum of all elements in the array.

In JavaScript, the for loop is a control flow statement that allows you to iterate over a given array, object, or string. The for loop will execute a set of statements for each element in the array, object, or string. In this tutorial, we will discuss the benefits of finding the sum of all elements of a given array using the for a loop.

One of the benefits of using the for loop to find the sum of all elements in an array is that it is easy to code. You simply need to create a variable to store the sum, and then use the for loop to iterate over the array, adding each element to the sum. This is a very concise way to find the sum of an array.

## Example 1

Below is the complete program to sum all elements in an array using for loop −

<!doctype html> <html> <head> <title>Examples</title> </head> <body> <h2> Finding sum of all elements using <i>for</i> loop: </h2> <div id="array"></div> <div id="result"></div> <script> const data = [2,4,6,8]; let sum = 0; const len = data.length for (let i = 0; i < len; i++) { sum += data[i]; } document.getElementById("array").innerHTML = "Array = [" + data+ "]"; document.getElementById("result").innerHTML ="Sum of All Elements: " + sum; </script> </body> </html>

## Output

The code will give the below output.

Finding sum of all elements using for loop: Array = [2,4,6,8] Sum of All Elements: 20

There are some disadvantages of finding the sum of all elements of a given array in JavaScript using for loop. They are as follows −

It is a time-consuming process: Finding the sum of all elements of an array using for loop is a time-consuming process. This is because the loop has to iterate through all the elements of the array to find their sum.

It is a memory-consuming process: This is because, in order to find the sum of all elements of an array, all the elements have to be stored in the memory first and then the process of finding their sum is carried out. This consumes a lot of memory.

It is a processor-intensive process: This is because the loop has to iterate through all the elements of the array to find their sum.

## Using the reduce() method

To find the sum of all elements of an array, you can use the **reduce()** method. This method applies a function to each element in the array, from left to right, and returns a single value.

The **reduce()** method takes two arguments: a function and an optional initial value. The function is executed on each element in the array, and the return value is used as the new value for the next element in the array. The initial value is optional; if omitted, the first element in the array is used as the initial value.

If the array is empty, or if the initial value is specified and the array has only one element, the initial value is returned.

## Example 2

The example below is implementation using reduce() method −

<!doctype html> <html> <head> <title>Examples</title> </head> <body> <h2> Finding sum of all elements using <i>reduce()</i> method: </h2> <div id="array"></div> <div id="result"></div> <script> var arr = [2, 4, 6, 8]; var sum = arr.reduce(function(a,b){ return a+b; }, 0); document.getElementById("array").innerHTML = "Array: " + arr; document.getElementById("result").innerHTML = "Sum of all elements in the array = " + sum; </script> </body> </html>

## Output

The code will give the below output.

20Finding sum of all elements using reduce() method: Array: 2,4,6,8 Sum of all elements in the array = 20

There are many advantages to using the reduce() method to find the sum of all elements in an array. First, it is simple and concise. Second, it is easy to read and understand. Third, it is efficient and fast. Finally, it can be used to find the sum of any type of data, not just numbers.

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