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Warn developers about improper selector usage
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Give developers a gentle push in the right direction.

Nudge is an opinionated, ITCSS-compatible library that detects misuse of certain CSS selectors, and gives developers a subtle nudge to fix them. Mistakes and incorrect usage get highlighted in the UI.

Screenshot showing a simple example of Nudge at work


$ bower install --save-dev nudgecss


$ npm install --save-dev nudgecss

Disclaimers and Notices

  1. This is not an active OSS project. Please feel free to use Nudge in your projects, but be aware that this repository exists mainly for me and my clients to use in our work. It’s opinionated, has limited scope, and is not actively seeking contributions. If do have something you feel is a worthy addition within this scope, open an issue.
  2. This is crude. Very crude. The CSS in Nudge is actively bad. It’s circumstantial at best. Nudge is intended to be a very loose, high-level linter, and probably will miss things or give false positives. I’m okay with that—I just want Nudge to be a quick ’n’ dirty, cheap ’n’ cheerful first pass over the UI. For what it needs to do, Nudge is GoodEnough™ for now. More strict and stringent tools should be used if that’s what you require.
  3. Remove Nudge from production. Nudge will fill your stylesheet full of crap: please make sure you remove Nudge before putting any CSS live. This will help performance, but will also ensure that your users never see any errors or breakages that your developers have missed.


Using Nudge is relatively simple. For more in-depth information and documentation, please see the comments in the relevant files.

Including in your project

  • @import _tools.nudge.scss into your Tools layer (if you are not using ITCSS, @import it somewhere toward the beginning of your project).
  • @import _trumps.nudge.scss into your Trumps layer (if you are not using ITCSS, @import it somewhere toward the end of your project).


You can disable Nudge features by setting $nudge-[feature] to false just before you @import _tools.nudge.scss, e.g.:

$nudge-single-spaces:         false;
$nudge-underscores:           false;
$nudge-camel-case:            false;
@import "tools.nudge";

This will stop Nudge from reporting on the use of single spaces in class attributes, the use of underscores in class names, and the use of camel case in class names.

Incorrect Nesting

To check for incorrect nesting of a class, call the nudge-nest() mixin within it, passing in the expected ancestor. For example, in our HTML, .widget__title must always live inside of .widget, so in our Sass we would write:

.widget {

  .widget__title {
    @include nudge-nest('.widget');

Now we will see an error in our UI if .widget__title is used outside of the context of .widget.

Deprecated Selectors

To configure our deprecated selectors, simply copy/paste the $nudge-deprecated-selectors-list map out of _trumps.nudge.scss and into your manifest file (e.g. main.scss). Place it just before your @import for the _trumps.nudge.scss file, then delete the !default flag and replace the example selectors with your own, e.g.:

$nudge-deprecated-selectors-list: (
  '.btn': '.c-btn',
@import "trumps.nudge";

The Rules

  • Incorrect Nesting: Check that a selector hasn’t been used outside of its required context. Display an error if it has.
  • No IDs We shouldn’t use IDs in CSS, so display a warning any time we find one.
  • Single-Space Delimited class Attributes: Prefer two spaces separating individual strings in the class attribute. Display a warning if we find single spaces.
  • Improper Use of BEM Modifiers: Display an error if someone tries to use a Modifier without also having defined a Block.
  • Underscores as Delimiters: We use hyphens to delimit strings, so display a warning if we find any classes with single hyphens.
  • Use of Camel Case: We do not use camel case, so display a warning if we find any capital letters in a class.
  • Deprecated Selectors: Display a warning if we find any classes that we have deemed deprecated.
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