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## Overview
In this shot, we’ll discuss three ways to sum up all the numbers in a given range in JavaScript.

Our program should accept an array of two numbers as input, for example, `sumAll([1, 3])`. Then, it should process the sum of all the numbers in the given range. It should be noted that both the numbers in the given range are inclusive, that is, `1` and `3` in this example. Finally, the program should return the total/sum as output, which is `6` in the case of this example.

The lowest number will not always come first. Hence, `[3,1]` should be treated as `[1,3]`.




## How to use the traditional `for` loop


function sumAll(arr) {
  if (arr[0] > arr[1]) // if the highest number is on the left, sort the array
    arr.sort((a, b) => a - b)

  let sum = 0 // Initialize a variable that will be holding the sum

  for (let i = arr[0]; i <= arr[1]; i++) // Loop over the range
    sum += i
  
  return sum // return result
}

console.log(sumAll([3,1]))

## How to use the `.reduce()` method
Here we will implement:

- Generate all the array items in the provided range. For example, `[1, 4]` => `[1, 2, 3, 4]`.
- Get the [sum by using the `reduce()`](https://www.educative.io/answers/how-to-sum-a-javascript-array-with-reduce) method.


function sumAll(arr) {
  if (arr[0] > arr[1])
    arr.sort((a, b) => a - b)

  const newArr = [] 
  
  for(let i = arr[0]; i <= arr[1]; i += 1) 
    newArr.push(i)

  return newArr.reduce((acc, cur) => acc + cur)
}

console.log(sumAll([3,1]))

We can also use [methods](https://www.educative.io/answers/how-to-get-the-sum-of-an-array-in-javascript) other than `reduce()` to get the sum of the newly created array items.

Happy coding!

How to sum up all the numbers in a range in JavaScript

Sum numbers in a given range in JavaScript using for loop or .reduce() method.

How to sum up all the numbers in a range in JavaScript

Overview

How to use the traditional for loop

How to use the .reduce() method

How to use the traditional `for` loop

How to use the `.reduce()` method