Add command-line cli

bin/cli.js

@@ -0,0 +1,14 @@
+#!/usr/bin/env node
+
+import { calculate } from '../dist/esm/index.js';
+
+const selector = process.argv[2];
+if (selector) {
+  const { A, B, C } = calculate(selector);
+  const formatted = `${A},${B},${C}`;
+  console.log(formatted);
+} else {
+  console.log('Usage: specificity <selector>');
+  console.log('Computes the specificity of a CSS selector.');
+  process.exit(1);
+}

package.json

@@ -31,6 +31,9 @@
     },
     "./package.json": "./package.json"
   },
+  "bin": {
+    "specificity": "./bin/cli.js"
+  },
   "scripts": {
     "prebuild": "rm -rf ./dist",
     "build": "tsc -b ./tsconfig.json ./tsconfig.cjs.json && cp package-cjs.json dist/cjs/package.json",

readme.md

@@ -76,3 +76,20 @@ Returns `0` if `a` has the same specificity than `b`
 ## compareDesc(a, b)
 
 Same as `compare` but returns the opposite value, for use in sorting specificity objects with the highest specificity first.
+
+## Command-line usage
+
+Run `npm install specificity` to install the module locally, or `npm install -g specificity` for global installation. Run `specificity` without arguments to learn about its usage:
+
+```
+$ specificity
+Usage: specificity <selector>
+Computes the specificity of a CSS selector.
+```
+
+Pass a selector as the first argument to get its specificity computed:
+
+```
+$ specificity "ul#nav li.active a"
+1,1,3
+```