# About this series

This is series of daily JavaScript coding challenges... for both beginners and advanced users.

Each day I’m gone present you a very simple coding challenge, together with the solution. The solution is intentionally written in a didactic way using classic JavaScript syntax in order to be accessible to coders of all levels.

Solutions are designed with increase level of complexity.

## Today’s coding challenge

```
Create a function to calculate the sum of all the numbers in a jagged array (array contains numbers or other arrays of numbers on an unlimited number of levels)
```

(scroll down for solution)

## Code newbies

If you are a code newbie, try to work on the solution on your own. After you finish it, or if you need help, please consult the provided solution.

## Advanced developers

Please provide alternative solutions in the comments below.

You can solve it using functional concepts or solve it using a different algorithm... or just solve it using the latest ES innovations.

By providing a new solution you can show code newbies different ways to solve the same problem.

## Solution

```
// Solution for challenge45
var ar = [1, 2, [15, [23], [5, 12]], [100]];
println(sumArray(ar));
function sumArray(ar)
{
var sum = 0;
for(var el of ar)
{
if (Array.isArray(el))
{
el = sumArray(el);
}
sum += el;
}
return sum;
}
```

To quickly verify this solution, copy the code above in this coding editor and press "Run".

Note: The solution was originally designed for codeguppy.com environment, and therefore is making use of

`println`

. This is the almost equivalent of`console.log`

in other environments. Please feel free to use your preferred coding playground / environment when implementing your solution.

## Discussion

Using ES10

`Array.flat()`

to flatten arrayES10 is where it's at! Love this solution!

Using toString to flatten the array:

Using recursive JavaScript: