How to find the sum of an array of numbers

Question

Given an array [1, 2, 3, 4], how can I find the sum of its elements? (In this case, the sum would be 10.)

I thought $.each might be useful,

Answer 1

OK, imagine you have this array below:

const arr = [1, 2, 3, 4];

Let's start looking into many different ways to do it as I couldn't find any comprehensive answer here:

1) Using built-in reduce()

function total(arr) {
  if(!Array.isArray(arr)) return;
  return arr.reduce((a, v)=>a + v);
}

2) Using for loop

function total(arr) {
  if(!Array.isArray(arr)) return;
  let totalNumber = 0;
  for (let i=0,l=arr.length; i

3) Using while loop

function total(arr) {
  if(!Array.isArray(arr)) return;
  let totalNumber = 0, i=-1;
  while (++i < arr.length) {
     totalNumber+=arr[i];
  }
  return totalNumber;
}

4) Using array forEach

function total(arr) {
  if(!Array.isArray(arr)) return;
  let sum=0;
  arr.forEach(each => {
    sum+=each;
  });
  return sum;
};

and call it like this:

total(arr); //return 10

It's not recommended to prototype something like this to Array...