Finding every first array in nested array

Question

I have a function that sometimes generates a nested array (for multiPolygon purposes). It could look like this:

[
  [
    [ 10.0, 59.0],
    [ 10.0, 59.0],
    [ 10.0, 59.0]
  ],
  [
    [ 10.0, 59.0],
    [ 10.0, 59.0],
    [ 10.0, 59.0]
  ]
]

So it could return a nested array with multiple nested arrays inside. But i want to make shure that i only get the first nested array, like this:

[
  [
    [ 10.0, 59.0],
    [ 10.0, 59.0],
    [ 10.0, 59.0]
  ]
]

Im developing in NodeJS.

Answer 1

A simple recurrence function which looks for another arrays solves it. It works with infinitely nested arrays and use object type protection.

function getFirstArray(array){
  var hasArrays = false;
  for (i in array) {
    if(typeof(array[i]) == "object"){
      return getFirstArray(array[i]);
      hasArrays = true;
      break;
    }
  }
  if(!(hasArrays)){
    return array;
  }
}

Then use it simply as:

var firstArray = getFirstArray(matrix);
console.log(firstArray);

Hope this helps :)