Array.prototype.flat() is not working in command line using Node JS

Question

I am trying to test the array.flat method inside Visual Studio code using node js from the command line. When I run the code i get:

"TypeError: arr.flat is not a function"

I have ran the code in chrome and am able to get the desired result (a flattened array)

Note: Even after updating node js to the latest version, it is still not working.

var arr1 = [1, 2, [3, 4]];
arr1.flat(); 
console.log(arr1)

`.flat()` creates a *new* array and returns it. It does not modify the source array. — Pointy, Aug 23 '19 at 03:25
Possible duplicate of [.flat() is not a function, what's wrong?](https://stackoverflow.com/questions/50993498/flat-is-not-a-function-whats-wrong) — Monarth Sarvaiya, Aug 23 '19 at 03:32
When you say you updated Node to the latest version, which version was that? — Ry-, Aug 23 '19 at 04:54

yqlim · Accepted Answer · 2019-08-24T06:05:39.997

10

Only NodeJS version 11 and above support this method. Please note that the current LTS Node version is only at 10.16.3, which does not support this.

Check the compatibility table.

To check what version use this:

node --version

If you Node version is below 11, you will need to upgrade it to use it.

Note

Node versions that use odd number major versions (i.e., v11.x.x, v13.x.x) are generally perceived as a test version and should not be used for production applications. Use even number major versions (i.e., v10.x.x, v12.x.x) instead.

edited Aug 24 '19 at 06:05

answered Aug 23 '19 at 04:16

yqlim

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@TylerMorales: Don’t update to v11, v11 is outdated. The latest Node is 12.9.0. – Ry- Aug 23 '19 at 15:50
@yqlim Thanks for the answer. Would just to add that the command node -v is the short form of node --version, So both can be used :) – Imran Rafiq Rather Apr 02 '20 at 16:37

Array.prototype.flat() is not working in command line using Node JS

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