How to tell whether running in a browser or in NodeJS?

Question

What is the best way for Javascript code to tell whether it is running in a browser or in NodeJS?

I'm looking for something which will evaluate to a boolean.

Trying to access window and catching the exception seems rather clinky. Is there a better way?

No exception involved; `nodal = (typeof window === 'undefined');` — Alex K., Nov 04 '14 at 15:32
Why don't you check process.version which in node gives the following output: { http_parser: '1.0', node: '0.10.4', v8: '3.14.5.8', ares: '1.9.0-DEV', uv: '0.10.3', zlib: '1.2.3', modules: '11', openssl: '1.0.1e' } — matteo, Nov 04 '14 at 15:34
Here's the block we use for Node/AMD/Browser detection ([link](https://github.com/geraintluff/tv4/blob/master/tv4.js#L10-L19)) - instead of a boolean (there are more than two kinds of setup), it calls the initialisation function in different configurations. — cloudfeet, Nov 04 '14 at 15:34
http://timetler.com/2012/10/13/environment-detection-in-javascript/ — Cory Danielson, Nov 04 '14 at 16:07

score 4 · Accepted Answer · answered Nov 04 '14 at 15:36

4

You could use a cut down version of the UMD method:

var isNode = (typeof exports === 'object') ? true: false;

answered Nov 04 '14 at 15:36

Andy

8

Why return a bool for something that's going to evaluate to a bool anyway? `var isNode = typeof exports !== 'object';` – Ben Fortune Nov 04 '14 at 15:38
1

I think my version is clearer. – Andy Nov 04 '14 at 15:39
1

How can you be sure that in the future the 'exports' variable is not going to represent an object browser side? – matteo Nov 04 '14 at 15:52
The common "cast to boolean" operator (which is still unnecessary, but at least makes the booleanness clear) is `!!`. `? true : false` is a strong code smell to most JavaScript devs. – Aaron Dufour Nov 04 '14 at 16:46
1

First I've heard of that. – Andy Nov 04 '14 at 16:53

score 0 · Answer 2 · answered Nov 04 '14 at 15:44

0

var isNode = (typeof processs != 'undefined' && typeof process.versions != 'undefined' && typeof process.versions.node != 'undefined');

answered Nov 04 '14 at 15:44

matteo

2 Answers2