For the life of me, I just can't figure out what I'm doing wrong here.

I'm trying to use both the reduce and concat array methods to take all of the values of a 2d array and combine them into a single value (basically condense them into a single array and then sum them up).

The problem that I keep running into is that when I try to make a for/loop to concat each array element, the argument that I'm passing into the function is not being recognized as an array, thus my call to .concat() is failing. I've placed a console.log() at the beginning of the function to see if the element is being recognized as the first array element in the 2d array, and it's coming up as "1"(?).

I tried another test outside of the function, and it logs as the actual array element. What am I doing wrong here? code below:

```
var arrays = [[1, 2, 3], [4, 5], [6]];

var myArray = arrays[0]; // Test
console.log(myArray); // Test

var flatArray = arrays.reduce(function(arrays)
{
    console.log(arrays[0]); // Test

    for (var i = 0; i < arrays.length - 1; i++)
    {
        arrays[0].concat(arrays[i+1]);
    }
    return arrays;

});

console.log(flatArray);

```

This is the output that I keep getting:

```
Array [ 1, 2, 3 ]
1
TypeError: arrays[0].concat is not a function

```

It's almost seems like array is being converted to a number-type when inside the function...?