Javascript check for empty array inside empty array?

Question

I have a variable

var test = [[[]]]

And I am wondering if there is an easy way to see if this is empty. While it's technically not empty, it is empty for my instance. Is there a way to check for this?

Can't you just check if the .length of the appropriate array is zero? — Andrew Morton
– Andrew Morton, Commented Jul 30, 2014 at 18:14

elclanrs · Accepted Answer · 2014-07-30 18:20:57Z

1

You could just deep flatten the array:

var flatten = function(xs) {
  var out = [].concat.apply([], xs)
  return xs.some(Array.isArray) ? flatten(out) : out
}

var isEmpty = function(xs) {
  return !flatten(xs).length
}

isEmpty([[[]]]) //=> true
isEmpty([[[]], [[]]]) //=> true

answered Jul 30, 2014 at 18:20

elclanrs

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1 Comment

cwharris Over a year ago

beat me to it. Yay for functional.

jgillich · Accepted Answer · 2014-07-30 18:19:35Z

0

Using Array.prototype.filter:

var arr = [[], [], []];
var isEmpty = arr.filter(function (arr) { return arr.length != 0; }).length === 0;
// isEmpty == true

var arr = [[], [], [1,2,3]];
var isEmpty = arr.filter(function (arr) { return arr.length != 0; }).length === 0;
// isEmpty == false

answered Jul 30, 2014 at 18:19

jgillich

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