freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/sum-all-numbers-in-a-range.english.md

id, title, isRequired, challengeType, forumTopicId

id	title	isRequired	challengeType	forumTopicId
a3566b1109230028080c9345	Sum All Numbers in a Range	true	5	16083

Description

We'll pass you an array of two numbers. Return the sum of those two numbers plus the sum of all the numbers between them. The lowest number will not always come first.

For example, sumAll([4,1]) should return 10 because sum of all the numbers between 1 and 4 (both inclusive) is 10.

Instructions

Tests

tests:
  - text: <code>sumAll([1, 4])</code> should return a number.
    testString: assert(typeof sumAll([1, 4]) === 'number');
  - text: <code>sumAll([1, 4])</code> should return 10.
    testString: assert.deepEqual(sumAll([1, 4]), 10);
  - text: <code>sumAll([4, 1])</code> should return 10.
    testString: assert.deepEqual(sumAll([4, 1]), 10);
  - text: <code>sumAll([5, 10])</code> should return 45.
    testString: assert.deepEqual(sumAll([5, 10]), 45);
  - text: <code>sumAll([10, 5])</code> should return 45.
    testString: assert.deepEqual(sumAll([10, 5]), 45);

Challenge Seed

function sumAll(arr) {
  return 1;
}

sumAll([1, 4]);

Solution

function sumAll(arr) {
  var sum = 0;
  arr.sort(function(a,b) {return a-b;});
  for (var i = arr[0]; i <= arr[1]; i++) {
    sum += i;
  }
  return sum;
}