Code files

Chapter03/watching-files-and-directories/watcher.js

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+'use strict'
+
+const fs = require('fs')
+const human = require('human-time')
+
+const interval = 5007
+const file = process.argv[2]
+let exists = false
+
+if (!file) {
+  console.error('supply a file')
+  process.exit(1)
+}
+
+const created = ({birthtime}) => 
+  !exists && (Date.now() - birthtime) < interval
+
+const missing = ({birthtime, mtime, atime, ctime}) => 
+  !(birthtime|mtime|atime|ctime)
+
+const updated = (cur, prv) => cur.mtime !== prv.mtime
+
+fs.watchFile(file, {interval}, (cur, prv) => {
+  if (missing(cur)) {
+    const msg = exists ? 'removed' : 'doesn\'t exist'
+    exists = false
+    return console.log(`${file} ${msg}`)
+  }
+
+  if (created(cur)) {
+    exists = true
+    return console.log(`${file} created ${human((cur.birthtime))}`)
+  }
+
+  exists = true
+
+  if (updated(cur, prv)) {
+    return console.log(`${file} updated ${human((cur.mtime))}`)
+  }
+
+  console.log(`${file} modified ${human((cur.mtime))}`)
+})
+
+