return the sum of an array

Returning the Sum of an Array#

If you have an array of numbers and you want to find the sum of all the numbers in the array, there are a couple of ways to accomplish this. One way is to use a for loop to iterate through the array and add up each number:

function sumArray(arr) {
  var sum = 0;
  for (var i = 0; i < arr.length; i++) {
    sum += arr[i];
  }
  return sum;
}

var myArray = [1, 2, 3, 4, 5];
var mySum = sumArray(myArray);
console.log(mySum);

In this code, we define a function called sumArray that takes an array as its argument. We then create a variable called sum and set it to 0. We use a for loop to iterate through each number in the array and add it to the sum variable. Finally, we return the sum variable.

To use this function, we create an array called myArray containing the numbers 1 through 5. We then call the sumArray function and pass in myArray as its argument. The result is stored in a variable called mySum, which we then log to the console.

Another way to find the sum of an array is to use the reduce method:

function sumArray(arr) {
  var sum = arr.reduce(function(a, b) {
    return a + b;
  }, 0);
  return sum;
}

var myArray = [1, 2, 3, 4, 5];
var mySum = sumArray(myArray);
console.log(mySum);

In this code, we define the sumArray function again. This time, we use the reduce method to iterate through the array and add up each number. The reduce method takes a function as its argument that is used to accumulate the result. In this case, the function takes two arguments, a and b, which represent the accumulated result and the current element of the array. The function returns the sum of a and b. We also pass in a second argument to reduce, which is the initial value of the accumulated result (in this case, 0). Finally, we return the result of the reduce method.

To use this function, we create an array called myArray containing the numbers 1 through 5. We then call the sumArray function and pass in myArray as its argument. The result is stored in a variable called mySum, which we then log to the console.