Get values of multidimensional array [duplicate]

Question

I want to get numbers from

var arr = [1,[2],[[3]],[[[4]]]];

using JavaScript/jQuery.

could be more in the series.

That is a horrible explanation of what you want to accomplish and doesn't identify any format for expected results. Please take the time to read How to Ask. Also please show what you have tried...this isn't a free code writing service — charlietfl
– charlietfl, Commented Apr 11, 2017 at 17:36
Granted, the question is poor, but it's not a dup of the article linked by @Brian. — John Vandivier
– John Vandivier, Commented Apr 11, 2017 at 17:38
@YuryTarabanko very similar, but different. A multidimensional array is more complex than an array of arrays (n=2). The answer accepted there will not flatten the n=4 dim array from hemant, it needs more recursion — John Vandivier
– John Vandivier, Commented Apr 11, 2017 at 17:41
You forgot to show us all the code that you wrote and explain specifically what's not working with it. — takendarkk
– takendarkk, Commented Apr 11, 2017 at 17:48

John Vandivier · Accepted Answer · 2017-04-11 17:37:09Z

0

You are looking for Array.prototype.reduce()

For example:

var arr = [1,[2],[[3]],[[[4]]]];

const flatten = arr => arr.reduce(
  (acc, val) => acc.concat(
    Array.isArray(val) ? flatten(val) : val
  ),
  []
);

console.log(flatten(arr));

answered Apr 11, 2017 at 17:37

John Vandivier

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2 Comments

Hemant Over a year ago

it is good, i did not know this function (flatten) but neither I know ECMAScript 6. Can you please explain me this in ECMAScript 5?

user4639281 Over a year ago

@Hermant without the use of ES6 fat arrow functions, the code would be:

const flatten = function(arr) {   return arr.reduce(     function(acc, val) {        return acc.concat(         Array.isArray(val) ? flatten(val) : val       );     },     []   ); };

score 0 · Accepted Answer · 2017-04-11 18:19:43Z

0

Realistically, if you only want to get the numbers you can just convert the array to a string then use a simple regex to extract all of the numbers:

console.log([1,[2],[[3]],[[[4]]]].toString().match(/\d+/g)); // ["1","2","3","4"]

If the result must be an array of numbers (not strings), you can use Array#map to run the conversion (e => +e).

console.log([1,[2],[[3]],[[[4]]]].toString().match(/\d+/g).map(e => +e)); // [1,2,3,4]

edited Apr 11, 2017 at 18:19

answered Apr 11, 2017 at 18:14

user4639281

7 Comments

John Vandivier Over a year ago

great solution, but critical assumption that strings are ok

user4639281 Over a year ago

@john edited to include example that returns numbers instead of strings.

John Vandivier Over a year ago

Again, very good solution, but still has a restricted use case. You can't flatten a multidiminsional array of objects using a .match() approach, for example. If OP has your use case, yours is ideal, but a truly generic flatten needs something like Array.prototype.reduce()

user4639281 Over a year ago

@John Of course, if they are looking for anything other than just the numbers, then a recursive flattening will need to happen. As I said in the first sentence of my answer, this is only applicable if they only want to get the numbers.

user4639281 Over a year ago

Not really understanding the downvote here.

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