add memory benchmark

Author: Bart Veneman

benchmark/memory.js

@@ -0,0 +1,49 @@
+import byteSize from './format-filesize.js'
+import { analyze as analyzeCss } from '../dist/analyzer.modern.js'
+import * as fs from 'fs'
+const files = [
+  ['bol-com-20190617', 'Bol.com', 117],
+  ['bootstrap-5.0.0', 'Bootstrap 5.0.0', 49],
+  ['css-tricks-20190319', 'CSS-Tricks', 50],
+  ['cnn-20220403', 'CNN', 360],
+  ['facebook-20190319', 'Facebook.com', 71],
+  ['github-20210501', 'GitHub.com', 95],
+  ['gazelle-20210905', 'Gazelle.nl', 312],
+  ['lego-20190617', 'Lego.com', 59],
+  ['smashing-magazine-20190319', 'Smashing Magazine.com', 285],
+  ['trello-20190617', 'Trello.com', 80]
+]
+
+let maxLen = -1
+
+files.forEach(([, name]) => {
+  if (name.length > maxLen) {
+    maxLen = name.length
+  }
+})
+
+console.log('Running benchmark on /dist/analyzer.js:')
+
+const suite = []
+
+files.forEach(([filename, name, expectedDuration]) => {
+  const css = fs.readFileSync(`./src/__fixtures__/${filename}.css`, 'utf-8')
+  const fileSize = byteSize(css.length)
+  suite.push([
+    `${name.padEnd(maxLen + 2)} (${fileSize.padStart(7)})`,
+    () => analyzeCss(css),
+    `${(process.memoryUsage().heapUsed / 1024 / 1024).toFixed(3)}MB`
+  ])
+})
+
+suite.forEach(([name, fn, memory]) => {
+  const start = new Date()
+  fn()
+  const duration = (new Date() - start)
+  console.log(
+    name,
+    `${duration}ms`.padStart(6, ' '),
+    memory,
+  )
+})
+