I have a nested array and need to reduce it to one dimensional array

Question

I want to reduce the dimensions of my array from array of arrays to a single array. The structure may be heavily nested.

I tried using reduce and map functions and running a loop, but it is very complicated. Wanted to know if there is a simpler solution

Input example:  a = [[1],[2,3,['abc']],[5,[6,['def']]]]
Output expected: a = [1, 2, 3, "abc", 5, 6, "def"]

Note: [See the second solution](https://stackoverflow.com/a/15030117/3149020) of the duplicate link as this works for nested arrays. — Spencer Wieczorek, Feb 06 '19 at 04:04
@CertainPerformance That isn't apart of the EMCAScript specs, so I highly discourage that until it moves out of being a proposal. — Spencer Wieczorek, Feb 06 '19 at 04:07
@SpencerWieczorek It will be; the proposal is finished, so one may as well use it, with the same approach as one would use for any semi-modern method; integrate a polyfill to ensure older browsers can understand it. — CertainPerformance, Feb 06 '19 at 04:09

score 1 · Accepted Answer · answered Feb 06 '19 at 04:00

I think this would be a great example to use the new flat function in arrays refer [https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/flat]

let a = [[1],[2,3,['abc']],[5,[6,['def']]]]
a = a.flat(Infinity);  // since the nesting may be highly deep

You can use a recommended polyfill since the browser support is not very high.

Alternatives are to use reduce and concat, which is explained in the link above.

//to enable deep level flatten use recursion with reduce and concat

var arr1 = [1,2,3,[1,2,3,4, [2,3,4]]];
function flattenDeep(arr1) {
   return arr1.reduce((acc, val) => Array.isArray(val) ? acc.concat(flattenDeep(val)) : acc.concat(val), []);
}
flattenDeep(arr1);// [1, 2, 3, 1, 2, 3, 4, 2, 3, 4]

score 0 · Answer 2 · answered Feb 06 '19 at 04:04

0

You can use flat with the level of nesting to make it a single array

var a= [[1],[2,3,['abc']],[5,[6,['def']]]];
console.log(a.flat(3))

answered Feb 06 '19 at 04:04

ellipsis

12,049
2
17
33

I have a nested array and need to reduce it to one dimensional array

2 Answers2