Replace lint-vars.sh with a Node.js script. (#24860)

Also, include it in the `css` npm script since it's instant.

build/lint-vars.js

@@ -0,0 +1,83 @@
+#!/usr/bin/env node
+
+/*!
+ * Script to find unused Sass variables.
+ *
+ * Copyright 2017 The Bootstrap Authors
+ * Copyright 2017 Twitter, Inc.
+ * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
+ */
+
+'use strict'
+
+const fs = require('fs')
+const path = require('path')
+const glob = require('glob')
+
+// Blame TC39... https://github.com/benjamingr/RegExp.escape/issues/37
+function regExpQuote(str) {
+  return str.replace(/[-\\^$*+?.()|[\]{}]/g, '\\$&')
+}
+
+let globalSuccess = true
+
+function findUnusedVars(dir) {
+  if (!(fs.existsSync(dir) && fs.statSync(dir).isDirectory())) {
+    console.log(`"${dir}": Not a valid directory!`)
+    process.exit(1)
+  }
+
+  console.log(`Finding unused variables in "${dir}"...`)
+
+  // A variable to handle success/failure message in this function
+  let unusedVarsFound = false
+
+  // Array of all Sass files' content
+  const sassFiles = glob.sync(path.join(dir, '**/*.scss'))
+  // String of all Sass files' content
+  let sassFilesString = ''
+
+  sassFiles.forEach((file) => {
+    sassFilesString += fs.readFileSync(file, 'utf8')
+  })
+
+  // Array of all Sass variables
+  const variables = sassFilesString.match(/(^\$[a-zA-Z0-9_-]+[^:])/gm)
+
+  console.log(`There's a total of ${variables.length} variables.`)
+
+  // Loop through each variable
+  variables.forEach((variable) => {
+    const re = new RegExp(regExpQuote(variable), 'g')
+    const count = (sassFilesString.match(re) || []).length
+
+    if (count === 1) {
+      console.log(`Variable "${variable}" is only used once!`)
+      unusedVarsFound = true
+      globalSuccess = false
+    }
+  })
+
+  if (unusedVarsFound === false) {
+    console.log(`No unused variables found in "${dir}".`)
+  }
+}
+
+function main(args) {
+  if (args.length < 1) {
+    console.log('Wrong arguments!')
+    console.log('Usage: lint-vars.js folder [, folder2...]')
+    process.exit(1)
+  }
+
+  args.forEach((arg) => {
+    findUnusedVars(arg)
+  })
+
+  if (globalSuccess === false) {
+    process.exit(1)
+  }
+}
+
+// The first and second args are: path/to/node script.js
+main(process.argv.slice(2))

build/lint-vars.sh

@@ -1,28 +0,0 @@
-#!/usr/bin/env bash
-#
-# Approach:
-# 1. Find variable declaration in the form of "$my-var: anyvalue"
-# 2. Loop through found variables and find occurrences of each variable in all sass files
-# 3. Filter out vars that occurred only once
-#
-# Run from command line with `build/lint-vars.sh scss`.
-#
-# Source: https://gist.github.com/badsyntax/6193491
-
-if [ -z "$1" ]; then
-	echo "Please specify a directory as the first argument."
-	exit 1
-fi
-if [ ! -d "$1" ]; then
-	echo "Not a valid directory."
-	exit 1
-fi
-
-echo "Finding unused variables. This might take some time..."
-
-vars=$(find "$1" -type f -name "*.scss" -exec grep --color=never -h '^$[a-zA-Z0-9_-][^:]*' {} \; | sed 's/$\([a-zA-Z0-9_-][^:]*\).*/\1/')
-
-for var in $vars; do
-	echo -n "Occurrences of \"\$$var\":"
-	find "$1" -type f -name "*.scss" -exec grep --color=never -h "$var" "{}" \; | wc -l
-done | grep ' 1$'