32

How can I determine if webpack.config.js was loaded via webpack vs webpack-dev-server?

mpen
  • 272,448
  • 266
  • 850
  • 1,236

5 Answers5

27

Update: The environment variable is changed to WEBPACK_SERVE.

The webpack dev server will now set the WEBPACK_DEV_SERVER environment variable, allowing for a more robust way to check.

const isDevServer = process.env.WEBPACK_DEV_SERVER;
Jian
  • 3,118
  • 2
  • 22
  • 36
Martin Barksten
  • 405
  • 6
  • 11
18

Either:

const isDevServer = process.argv[1].indexOf('webpack-dev-server') !== -1;

or:

const isDevServer = process.argv.some(v => v.indexOf('webpack-dev-server') !== -1);

or:

const isDevServer = process.argv.some(v => v.includes('webpack-dev-server'));

I've been using the latter to a great effect. One configuration FTW!

bjfletcher
  • 11,168
  • 4
  • 52
  • 67
  • or... `const isDevServer = process.argv.find(v => v.includes('webpack-dev-server'))` – Alex Gyoshev Aug 05 '16 at 14:15
  • 2
    One nitpick: the 2nd and 3rd options will actually set `isDevServer` to the value of the `argv` element that contained `'webpack-dev-server'`. Substitute `some` for `find` to ensure `isDevServer` is a boolean. – lawnsea Mar 21 '18 at 19:18
  • 1
    @lawnsea just seen this and you're right, `some` would be better. I've edited my answer and thank you :) – bjfletcher May 09 '20 at 13:58
7

I found one potential soluton:

var isDevServer = path.basename(require.main.filename) === 'webpack-dev-server.js';

credit

Community
  • 1
  • 1
mpen
  • 272,448
  • 266
  • 850
  • 1,236
  • 1
    I like this answer more. Alternatively you can do: `path.relative('', require.main.filename) == 'node_modules/webpack-dev-server/bin/webpack-dev-server.js'`. – x-yuri Nov 11 '17 at 18:28
6

Or use the Webpack Environment Variables:

// The webpack command line
webpack-dev-server --open --env.devServer

// webpack.config.js
module.exports = env => {
  console.log('isDevServer: ', env.devServer) // true
  ...
}
Guillaume
  • 111
  • 1
  • 5
0

In general, webpack-dev-server runs with mode='development' (https://webpack.js.org/configuration/mode/#root), while webpack runs with mode=production. If so, you can use the value of:

process.env.NODE_ENV
Guillermo Constantino
  • 1