JavaScript: How to remove all the square brackets inside the outer array?

Question

var arrayX = [ ["fire", "lightning"], [3, "ice"], [85], ["wind", "earth", 0] ];

In the example above, arrayX consists of four elements, each of which is also an array. As it stands now, arrayX.length equals 4.

I wonder if it is possible to remove all the four pairs of square brackets inside, leaving only the most outer bracket, so that the computer can now count the total number of all the individual elements in arrayX. I mean, like this:

var arrayX = ["fire", "lightning", 3, "ice", 85, "wind", "earth", 0];

Now, arrayX.length returns 8, and this is the number I want to get. I started to learn programming just several days ago, so I'm not sure how to go about this. Thank you in advance.

Create an array and add all the elements to it, by traversing the original array using [for](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/for) loop, or use `arrayX.join().split(',')` but here all the values are converted to string, but `length` will be 8, as per the question. — rajuGT, Dec 11 '15 at 15:13

score 8 · Answer 1 · answered Dec 11 '15 at 15:13

8

There is no need to loop

arrayX = [].concat.apply([], arrayX);

answered Dec 11 '15 at 15:13

epascarello

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it works only if the array is not nested. – Nina Scholz Dec 11 '15 at 15:29
1

@NinaScholz Works fine for OPs case. I love when people add new requirements that do not matter in the OPs case. – epascarello Dec 11 '15 at 15:34

score 1 · Answer 2 · answered Dec 11 '15 at 15:12

1

Use Array.prototype.reduce():

var flattened = [ ["fire", "lightning"], [3, "ice"], [85], ["wind", "earth", 0] ].reduce(function(a, b) {
  return a.concat(b);
}, []);

docs here

answered Dec 11 '15 at 15:12

bcr

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Andrew Bone · Answer 3 · 2019-08-05T08:49:19.423

0

I'm a fan of the concat method myself

function concatArray() {
  var arrayX = [
    ["fire", "lightning"],
    [3, "ice"],
    [85],
    ["wind", "earth", 0]
  ];
  arrayX = [].concat.apply([], arrayX);
  console.log(arrayX.length);
}

concatArray();

edited Aug 05 '19 at 08:49

answered Dec 11 '15 at 15:18

Andrew Bone

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Was my answer wrong? – Andrew Bone Dec 12 '15 at 18:20
you seem happy , no one here likes that in my exp, avoid 'fan' , 'excelent', 'super' keywords – arnoldssss Feb 09 '19 at 00:37

JavaScript: How to remove all the square brackets inside the outer array?

3 Answers3