add --file-change-hook flag

Author: yi-ge

README.md

@@ -52,6 +52,7 @@ Look up flags and options can be used [in ts-node's docs](https://github.com/Typ
 * `--rs` - Allow to restart with "rs" line entered in stdio, disabled by default.
 * `--notify` - to display desktop-notifications (Notifications are only displayed if `node-notifier` is installed).
 * `--cache-directory` - tmp dir which is used to keep the compiled sources (by default os tmp directory is used)
+* `--file-change-hook` - Bind a file watch hook.
 
 If you need to detect that you are running with `ts-node-dev`, check if `process.env.TS_NODE_DEV` is set.
 

src/bin.ts

@@ -94,6 +94,7 @@ const devFlags = {
     'debounce',
     'watch',
     'cache-directory',
+    'file-change-hook'
   ],
 }
 
@@ -117,6 +118,7 @@ type DevOptions = {
   'exec-check': boolean
   'exit-child': boolean
   'cache-directory': string
+  'file-change-hook': string
   'error-recompile': boolean
   quiet: boolean
   'tree-kill': boolean

src/index.ts

@@ -1,6 +1,8 @@
 import { fork, ChildProcess } from 'child_process'
 import chokidar from 'chokidar'
 import fs from 'fs'
+import path from 'path'
+import vm from 'vm'
 import readline from 'readline'
 
 const kill = require('tree-kill')
@@ -240,6 +242,25 @@ export const runDev = (
     } else {
       notify('Restarting', file + ' has been modified')
     }
+
+    if (opts['file-change-hook']) {
+      const scriptPath = path.resolve(process.cwd(), opts['file-change-hook'])
+      const code = `require("${scriptPath}").default("${file}");`
+      try {
+        const result = vm.runInNewContext(code, {
+          require: require("esm")(module),
+          module,
+          console
+        });
+        if (!result) {
+          notify('FileChangeHook', 'Hook exit code: 0.')
+        }
+      } catch (err) {
+        notify('FileChangeHook', err)
+        console.log(err)
+      }
+    }
+
     compiler.compileChanged(file)
     if (starting) {
       log.debug('Already starting')

test/fixture/fileChangHook.js

@@ -0,0 +1,4 @@
+export default function (file) {
+  console.log('change file:' + file);
+  return 0
+}

test/tsnd.test.ts

@@ -66,7 +66,7 @@ describe('ts-node-dev', function () {
     await ps.waitForLine(/\[ERROR\]/)
     const out = ps.getStdout()
     const err = ps.getStderr()
-    
+
     t.ok(/Compilation error in/.test(err), 'Reports error file')
     t.ok(/[ERROR].*Unable to compile TypeScript/.test(out), 'Report TS error')
     t.ok(/Argument of type/.test(out), 'Report TS error diagnostics')
@@ -159,7 +159,7 @@ describe('ts-node-dev', function () {
     await ps.waitForLine(/JS MODULE/)
     t.ok(true, 'ok')
     await ps.exit()
-  })  
+  })
 
   it('should handle -r esm option and load JS modules', async () => {
     const ps = spawnTsNodeDev([`--respawn`, `-r esm`, `js-module.js`].join(' '))
@@ -361,4 +361,15 @@ describe('ts-node-dev', function () {
     const list = fs.readdirSync(cacheDir)
     t.ok(list[0] === 'compiled', '"compiled" dir is there')
   })
+
+  it('should handle --file-change-hook flag', async () => {
+    writeFile('test.ts', 'a')
+    const ps = spawnTsNodeDev([`--file-change-hook`, `fileChangHook.js`, `--respawn`, `--watch`, `test.ts`, `simple.ts`].join(' '))
+    await ps.waitForLine(/v1/)
+    writeFile('test.ts', 'b')
+    await ps.waitForLine(/Restarting.*test.ts/)
+    t.ok(true, 'works')
+    await ps.exit()
+    await removeFile('test.ts')
+  })
 })