Convert 2D Array Into 1D Array

Question

I have this 2 dimensional array:

var list = [
    ['zone_1', 'zone_2'],
    ['zone_3']
]

I want to merge all elements in the sub-arrays into a single array:

var list = [
    'zone_1',
    'zone_2',
    'zone_3'
]

How can I do that in node.js? It is possible to do it without using a loop or map?

`I don't want to use loop or map` Why not? Handy language tools are there to be used. An easy single-depth flatmap can be done via `const output = [].concat(...input.map(arr => arr));` — CertainPerformance, Apr 18 '18 at 00:52
You can also find what you want at here. https://stackoverflow.com/questions/10865025/merge-flatten-an-array-of-arrays-in-javascript — Tanaike, Apr 18 '18 at 00:55

score 9 · Accepted Answer · answered Apr 18 '18 at 00:52

9

The array .concat method is variadic, and you can use the spread operator to pass each sub-array to it as a separate argument. This makes flattening an array turn into a nice one-liner:

const arr = [ ['zone_1', 'zone_2'], ['zone_3'] ];
console.log([].concat(...arr))

answered Apr 18 '18 at 00:52

CRice

29,968
4
57
70

Thank you very much CRice. It works now. It is the one that I wanted. – Instasea Apr 18 '18 at 04:24

score 7 · Answer 2 · answered Jan 06 '20 at 17:19

7

Array.prototype.flat() The flat() method creates a new array with all sub-array elements concatenated into it recursively up to the specified depth.

const arr = [ ['zone_1', 'zone_2'], ['zone_3'] ];
console.log(arr.flat());

answered Jan 06 '20 at 17:19

sanjoyAudhikari

71
1
1

Convert 2D Array Into 1D Array

2 Answers2