Better way to use Modernizr with Command Line Config

Modernizr is a useful JavaScript library to detect user browser capabilities on websites. We use it on most of our projects to provide the best experience on different user devices.

Modernizr has 259 built-in feature detections. The minified file with all detections included is 90.65 kB in size. That’s quite big, specially considering that the file is added in the <head> of the HTML document.

This is why most developers hand-pick features as needed from the Modernizr website to include in the library. The process is manual and can take time, but now there is a better way.

Command Line Config

Modernizr has shipped with a feature called Command Line Config. It helps to automate the process, backed up by a Modernizr NPM module. This module should be installed globally on the developer’s machine, example:

npm i -g modernizr

Next step is to create a config file at the root of the project and call it something like modernizr-config.json. Here is an simple example of a config file.

  "options": [
  "feature-detects": [

When you need to add a new feature detections, there is no need to head over to the Modernizr website and manually generate a new file.

Simply define what you need in the config file. You can look at the example file with all features included to see what’s possible.


The last step of the process is to generate a new modernizr.js file to a desired folder in the project. Run the following command.

modernizr -c modernizr-config.json -d path/to/lib/ -u
  • -c stands for config
  • -d is for the destination folder
  • -u is to uglify/minify the output

Thanks to the Modernizr team to improve our process.

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