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?

• CertainPerformance: 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));
• Tanaike: You can also find what you want at here. stackoverflow.com/questions/10865025/…
• Hassan Imam: What about using list[0]?

Answer 1

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))

• Instasea: Thank you very much CRice. It works now. It is the one that I wanted.

Answer 2

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());