Question

160

Using es6 spread to concat multiple arrays

rated 0 times [ 161] [ 1] / answers: 1 / hits: 87020 / 7 Years ago, mon, april 17, 2017, 12:00:00

We all know you can do:

let arr1 = [1,2,3];

let arr2 = [3,4,5];

let arr3 = [...arr1, ...arr2]; // [1,2,3,3,4,5]

But how do you make this dynamic to concat N arrays?

Answers

Only authorized users can answer the question. Please sign in first, or register a free account.

bradleymoisesy

Add To Favorites

Follow

Total Points: 121

Total Questions: 105

Total Answers: 95

Location: Nepal

Member since Mon, Jan 4, 2021

3 Years ago

bradleymoisesy questions

1 which data type to use to expect date value in jest

Wed, Dec 22, 21, 00:00, 2 Years ago

1 React/Next.js doesn't seem to work with Apexcharts

Tue, Jun 1, 21, 00:00, 3 Years ago

1 React chart : prevent chart's canvas scaling with height and width

Mon, Feb 1, 21, 00:00, 3 Years ago

1 How to create Create an Excel File with javascript?

Thu, Jun 11, 20, 00:00, 4 Years ago

1 How to create a search filter using Vue js from API Data?

Thu, Jan 16, 20, 00:00, 4 Years ago

View All

answered 7 Years ago anabeldaliad · Accepted Answer

One option is to use reduce:

let arrs = [[1, 2], [3, 4], [5, 6]];

arrs.reduce((a, b) => [...a, ...b], []);

Of course, this is a slow solution (quadratic time). Alternatively, if you can use Lodash, _.flatten does exactly what you want, and does it more efficiently (linear time).

EDIT

Or, adapted from Xotic750's comment below,

[].concat(...arrs);

Which should be efficient (linear time).