I am trying to improve the DEV experience in my Node. To do that, I want to:
a) restart my server when server-side code is changed
b) refresh the browser when client-side code is changes. In an effort to accomplish this, I began integrating nodemon and browserSync into my gulp script.
In my gulp script, I have the following task:
gulp.task('startDevEnv', function(done) {
// Begin watching for server-side file changes
nodemon(
{ script: input.server, ignore:[input.views] })
.on('start', function () {
browserSync.init({
proxy: "http://localhost:3002"
});
})
;
// Begin watching client-side file changes
gulp.watch([ input.css, input.js, input.html ], function() { browserSync.reload(); });
done();
});
When the above task runs, my browser opens to http://localhost:3000/. My app is visible as expected. However, in the console window, I notice:
Error: listen EADDRINUSE :::3002
I understand to some extend. I have app.set('port', process.env.PORT || 3002); in my server.js file. Yet, I thought that was purpose of setting the proxy value. Still, whenever I make a code change, I see the following related error in my console window:
[07:08:19] [nodemon] restarting due to changes...
[07:08:19] [nodemon] starting `node ./dist/server.js`
events.js:142
throw er; // Unhandled 'error' event
^
TypeError: args.cb is not a function
at Object.init (/Users/me/Website/Develop/node_modules/browser-sync/lib/public/init.js:25:25)
at null.<anonymous> (/Users/me/Website/Develop/gulpfile.js:142:25)
at emitNone (events.js:73:20)
at emit (events.js:167:7)
at Object.run (/Users/me/Website/Develop/node_modules/nodemon/lib/monitor/run.js:97:7)
at Function.run.kill (/Users/me/Website/Develop/node_modules/nodemon/lib/monitor/run.js:221:7)
at null.<anonymous> (/Users/me/Website/Develop/node_modules/nodemon/lib/monitor/run.js:333:7)
at emitOne (events.js:83:20)
at emit (events.js:170:7)
at restartBus (/Users/me/Website/Develop/node_modules/nodemon/lib/monitor/watch.js:162:7)
Me-MBP:Develop me$ events.js:142
throw er; // Unhandled 'error' event
^
Error: listen EADDRINUSE :::3002
at Object.exports._errnoException (util.js:856:11)
at exports._exceptionWithHostPort (util.js:879:20)
at Server._listen2 (net.js:1238:14)
at listen (net.js:1274:10)
at Server.listen (net.js:1370:5)
at Object.<anonymous> (/Users/me/Website/Develop/dist/server.js:70:8)
at Module._compile (module.js:399:26)
at Object.Module._extensions..js (module.js:406:10)
at Module.load (module.js:345:32)
at Function.Module._load (module.js:302:12)
At this point, my code changes do not appear in my browser. I do not understand what I'm doing wrong. I suspect I have my ports misconfigured. But, I'm not really sure how they should be setup.
By default BrowserSync uses port 3000. BrowserSync also uses port 3001 for the BrowserSync UI. For these two reasons, I thought I would set the port to 3002 in my server.js file and create the proxy shown above. What am I doing wrong?
You actually don't need to use gulp for this to work.
a) restart my server when server-side code is changed
Install nodemon globally using npm i -g nodemon then on your app folder do nodemon or nodemon ${index-file-of-your-app}.
b) refresh the browser when client-side code is changes.
Use browserify or webpack. I prefer using webpack; you may need to learn about the configuration a little bit but the good thing with webpack is that you don't need to refresh it. Once changes are found the changes will be reflected on the browser automatically. https://github.com/webpack/docs/wiki/hot-module-replacement-with-webpack
You can livereload both front and backend changes to the browser by using the 'livereload', 'connect-livereload', and 'nodemon' packages together. Also, this way you don't need Gulp or Grunt. Here's how the packages play together:
livereload opens a high port and notifies the browser of changed public files
connect-livereload monkey patches every served HTML page with a snippet that connects to this high port
nodemon is then used to restart the server on changed backend files
Set up livereload in Express
Set up the Express to both start livereload server watching the public directory and ping the browser during nodemon-induced restart:
const livereload = require("livereload");
const connectLivereload = require("connect-livereload");
// open livereload high port and start to watch public directory for changes
const liveReloadServer = livereload.createServer();
liveReloadServer.watch(path.join(__dirname, 'public'));
// ping browser on Express boot, once browser has reconnected and handshaken
liveReloadServer.server.once("connection", () => {
setTimeout(() => {
liveReloadServer.refresh("/");
}, 100);
});
const app = express();
// monkey patch every served HTML so they know of changes
app.use(connectLivereload());
Start Express with nodemon
Then you'd start the server with nodemon, for example, with a dedicated watch script by running npm run watch.
The key point here is to ignore the public directory that's already being watched by livereload. You can also configure files with non-default extensions, like pug and mustache, to be watched.
"scripts": {
"start": "node ./bin/www",
"watch": "nodemon --ext js,pug --ignore public"
},
You can read a longer explanation in "Refresh front and backend changes to browser with Express, LiveReload and Nodemon."
#mateeyow is right.
But if you want the browser to reload automaticaly, you also need livereload-plugin.
Enable webpack-hot-replacement only replace code in browser's memory, livereload-plugin do reload it.
See rock for example: https://github.com/orange727/rock/blob/master/app/templates/webpack/webpack.make.js#L255
Just as:
webpackConfig.plugins: [
new webpack.HotModuleReplacementPlugin(),
new LiveReloadPlugin({
appendScriptTag: true,
port: config.ports.livereload,
})];
I might be missing some context (e.g. I'm not sure what input represents), however, I think the npm module reload might solve your problem. Here's an example from the npm package page:
var express = require('express')
, http = require('http')
, path = require('path')
, reload = require('reload')
, bodyParser = require('body-parser')
, logger = require('morgan')
var app = express()
var publicDir = path.join(__dirname, '')
app.set('port', process.env.PORT || 3000)
app.use(logger('dev'))
app.use(bodyParser.json()) //parses json, multi-part (file), url-encoded
app.get('/', function(req, res) {
res.sendFile(path.join(publicDir, 'index.html'))
})
var server = http.createServer(app)
//reload code here
//optional reload delay and wait argument can be given to reload, refer to [API](https://github.com/jprichardson/reload#api) below
reload(server, app, [reloadDelay], [wait])
server.listen(app.get('port'), function(){
console.log("Web server listening on port " + app.get('port'));
});
The EADDRINUSE error is normally due to a connection already open on the specified port. This is probably due to a previous instance of the connection not being correctly closed when restarting the app.
Take a look at this gist and in particular try something like this in your gulp file:
'use strict';
var gulp = require('gulp');
var browserSync = require('browser-sync');
var nodemon = require('gulp-nodemon');
gulp.task('default', ['browser-sync'], function () {});
gulp.task('browser-sync', ['nodemon'], function() {
browserSync.init(null, {
proxy: "http://localhost:3002"
});
});
gulp.task('nodemon', function (cb) {
var started = false;
return nodemon({
script: 'app.js'
}).on('start', function () {
// to avoid nodemon being started multiple times
if (!started) {
cb();
started = true;
}
});
});
The story:
We have a team of testers working on automating end-to-end tests using protractor for our internal AngularJS application. Here is the task they usually run for "local" testing:
grunt.registerTask('e2e:local', [
'build:prod',
'connect:test',
'protractor:local'
]);
It runs the "build" task, starts a webserver and runs the e2e tests against the local build.
The build:prod task itself is defined as:
grunt.registerTask(
'build:prod', [
'clean',
'copy:all',
'copy:assets',
'wiredep',
'ngtemplates',
'useminPrepare',
'concat',
'ngAnnotate',
'autoprefixer',
'uglify',
'cssmin',
'copy:cssfix',
'usemin',
'copy:html',
'bowercopy',
'template:setProdVersion'
]
);
Here we have a lot of subtasks (it definitely could be improved, but this is how it looks now).
The problem:
Currently, it takes about 25 seconds for the build to complete. And, every time a person is running end-to-end tests, the build task is executed.
The question:
How can I run the build:prod task only if there are changes in src directory?
Note that the requirement here is to make it transparent for the testers who run the tests. I don't want them to remember when they need to perform a build and when not.
In other words, the process should be automated. The goal is to automatically detect if build is needed or not.
Note that ideally I would like to leave the build task as is, so that if it is invoked directly via grunt build:prod it would rebuild regardless of the datestamp of the previous build.
Thoughts and tries:
there is the closely related grunt-newer package, but, since we have a rather complicated build, having a clean task at the beginning, I'm not sure how to apply it in my case
what I was also thinking about is to, inside the e2e:local task, manually check the timestamps of the files inside dist and src and, based on that, decide if build:prod is needed to be invoked. I think this is what grunt-newer is doing internally
we started to use jit-grunt that helped to improve the performance
Here's an idea if you use git:
How about using something like grunt-gitinfo and using the last commit in HEAD as a base?
The idea is:
You create a new grunt task that checks for latest commit hash
You'd save this commit hash in a file that's added to gitignore (and is NOT in the clean folder, typically can be in root of repo)
Before saving to file, it'd check the value already in it (standard node fs module can do the read/write easily)
If the hash doesn't match, run build:prod task then save new commit hash
The testers build would depend on your new task instead of build:prod directly
Another option (still using git):
You can use something like grunt-githooks and create a git hook that runs after pull and calls the git build:prod, then you can remove it from the dependencies of the grunt task that testers run.
You might have another code to check for githook and install it if required though, which can be a one-time extra step for testers, or maybe baked into the grunt task they call.
I'm surprised noone has mentioned grunt-contrib-watch yet (it's in the gruntjs.com example file and I thought it was pretty commonly known!). From github: "Run predefined tasks whenever watched file patterns are added, changed or deleted." - heres a sample grunt file that would run your tasks any time any .js files are modified in src/ or in test/, or if the Gruntfile is modified.
var filesToWatch = ['Gruntfile.js', 'src/**/*.js', 'test/**/*.js'];
grunt.initConfig({
watch: {
files: filesToWatch,
tasks: ['build:prod',
'connect:test',
'protractor:local']
}
});
grunt.loadNpmTasks('grunt-contrib-watch');
You have your developers open a terminal and run grunt watch before they start modifying files, and every time those files are modified the tasks will automatically be run (no more going back to the terminal to run grunt build:prod every time).
It's an excellent package and I suggest you check it out. -- github -- npmjs.org
npm install grunt-contrib-watch --save-dev
Not the answer your are looking for with grunt, but this will be easy with gulp.
var fs = require('fs');
var gulpif = require('gulp-if');
var sourceChanged = fs.statSync('build/directory').mtime > fs.statSync('source/directory').mtime;
gulp.task('build:prod', function() {
if (!sourceChanged) {
return false;
}
return gulp.src('./src/*.js')
.pipe(.... build ....)
.pipe(gulp.dest('./dist/'));
});
Here's how we've done some Git HEAD sha work for our build. We use it to determine which version is currently deployed to our production environment - but I'm quite certain you could rework it to return a boolean and trigger the build if truthy.
Gruntfile.js
function getHeadSha() {
var curr, match, next = 'HEAD';
var repoDir = process.env.GIT_REPO_DIR || path.join(__dirname, '..');
try {
do {
curr = grunt.file.read(path.join(repoDir, '.git', next)).trim();
match = curr.match(/^ref: (.+)$/);
next = match && match[1];
} while (next);
} catch(ex) {
curr = 'not-found';
}
return curr;
}
grunt.initConfig({
replace: {
applicationVersion: {
src: '<%= config.dist %>/index.html',
overwrite: true,
replacements: [{
from: '{{APPLICATION_VERSION}}',
to: getHeadSha
}]
}
}
});
grunt.registerTask('build', {
'replace:applicationVersion',
/** other tasks **/
});
grunt.registerTask('e2e:local', {
'check_if_we_should_build',
/** other tasks **/
});
index.html
<html data-version="{{APPLICATION_VERSION}}">
<!-- -->
</html>
There's also the git-info package which would simplify this whole process, we're looking at switching over to that ourselves.
edit; I just noticed #meligy already pointed you in the direction of git-info. credit where credit is due.
I am not sure if its helpful or not but same things we have done it in our project using GULP framework. We have written a watcher in the gulp that continuously check for the source change and run a quick function to build the project. Its a Protractor Test case.
gulp.task('dome', function () {
gulp.src(["maintest.js"])
.pipe(notify("Change Found , Executing Scripts."))
.pipe(protractor({
configFile: "conf.js",
args: ['--baseUrl', 'http://127.0.0.1:8000']
})).on('error', function (e) {
throw e
});
})
gulp.task('default', function () {
gulp.watch('./webpages/*.js', ['dome']);
gulp.watch('maintest.js', ['dome']);
gulp.watch('conf.js', ['dome']);
});
Link to repo.
I don't have experience in protractor, but conceptually I think this could work.
What I could suggest is to set an alias in your ~/.cshrc to run the build commands only if a diff command returns true.
#./cshrc
alias build_on_diff 'diff -r branch_dir_1 branch_dir_2\
if ( $status == 1 ) then\
build:prod\
endif'
Just replace the diff command with whatever git uses, and it should work provided it returns a 1 status for differences detected. We apply a similar method at my workplace to avoid rebuilding files that haven't changed.
Any ideas on how I could implement an auto-reload of files in Node.js? I'm tired of restarting the server every time I change a file.
Apparently Node.js' require() function does not reload files if they already have been required, so I need to do something like this:
var sys = require('sys'),
http = require('http'),
posix = require('posix'),
json = require('./json');
var script_name = '/some/path/to/app.js';
this.app = require('./app').app;
process.watchFile(script_name, function(curr, prev){
posix.cat(script_name).addCallback(function(content){
process.compile( content, script_name );
});
});
http.createServer(this.app).listen( 8080 );
And in the app.js file I have:
var file = require('./file');
this.app = function(req, res) {
file.serveFile( req, res, 'file.js');
}
But this also isn't working - I get an error in the process.compile() statement saying that 'require' is not defined. process.compile is evaling the app.js, but has no clue about the node.js globals.
A good, up to date alternative to supervisor is nodemon:
Monitor for any changes in your node.js application and automatically restart the server - perfect for development
To use nodemon with version of Node without npx (v8.1 and below, not advised):
$ npm install nodemon -g
$ nodemon app.js
Or to use nodemon with versions of Node with npx bundled in (v8.2+):
$ npm install nodemon
$ npx nodemon app.js
Or as devDependency in with an npm script in package.json:
"scripts": {
"start": "nodemon app.js"
},
"devDependencies": {
"nodemon": "..."
}
node-supervisor is awesome
usage to restart on save for old Node versions (not advised):
npm install supervisor -g
supervisor app.js
usage to restart on save for Node versions that come with npx:
npm install supervisor
npx supervisor app.js
or directly call supervisor in an npm script:
"scripts": {
"start": "supervisor app.js"
}
i found a simple way:
delete require.cache['/home/shimin/test2.js']
If somebody still comes to this question and wants to solve it using only the standard modules I made a simple example:
var process = require('process');
var cp = require('child_process');
var fs = require('fs');
var server = cp.fork('server.js');
console.log('Server started');
fs.watchFile('server.js', function (event, filename) {
server.kill();
console.log('Server stopped');
server = cp.fork('server.js');
console.log('Server started');
});
process.on('SIGINT', function () {
server.kill();
fs.unwatchFile('server.js');
process.exit();
});
This example is only for one file (server.js), but can be adapted to multiple files using an array of files, a for loop to get all file names, or by watching a directory:
fs.watch('./', function (event, filename) { // sub directory changes are not seen
console.log(`restart server`);
server.kill();
server = cp.fork('server.js');
})
This code was made for Node.js 0.8 API, it is not adapted for some specific needs but will work in some simple apps.
UPDATE:
This functional is implemented in my module simpleR, GitHub repo
nodemon came up first in a google search, and it seems to do the trick:
npm install nodemon -g
cd whatever_dir_holds_my_app
nodemon app.js
nodemon is a great one. I just add more parameters for debugging and watching options.
package.json
"scripts": {
"dev": "cross-env NODE_ENV=development nodemon --watch server --inspect ./server/server.js"
}
The command: nodemon --watch server --inspect ./server/server.js
Whereas:
--watch server Restart the app when changing .js, .mjs, .coffee, .litcoffee, and .json files in the server folder (included subfolders).
--inspect Enable remote debug.
./server/server.js The entry point.
Then add the following config to launch.json (VS Code) and start debugging anytime.
{
"type": "node",
"request": "attach",
"name": "Attach",
"protocol": "inspector",
"port": 9229
}
Note that it's better to install nodemon as dev dependency of project. So your team members don't need to install it or remember the command arguments, they just npm run dev and start hacking.
See more on nodemon docs: https://github.com/remy/nodemon#monitoring-multiple-directories
Nodemon has been the go to for restarting server for file changes for long time. Now with Node.js 19 they have introduced a --watch flag, which does the same [experimental]. Docs
node --watch index.js
node-dev works great. npm install node-dev
It even gives a desktop notification when the server is reloaded and will give success or errors on the message.
start your app on command line with:
node-dev app.js
There is Node-Supervisor that you can install by
npm install supervisor
see http://github.com/isaacs/node-supervisor
You can use nodemon from NPM.
And if you are using Express generator then you can using this command inside your project folder:
nodemon npm start
or using Debug mode
DEBUG=yourapp:* nodemon npm start
you can also run directly
nodemon your-app-file.js
Hope this help.
There was a recent (2009) thread about this subject on the node.js mailing list. The short answer is no, it's currently not possible auto-reload required files, but several people have developed patches that add this feature.
With Node.js 19 you can monitor file changes with the --watch option. After a file is changed, the process is restarted automatically, reflecting new changes.
node --watch server.js
yet another solution for this problem is using forever
Another useful capability of Forever is that it can optionally restart
your application when any source files have changed. This frees you
from having to manually restart each time you add a feature or fix a
bug. To start Forever in this mode, use the -w flag:
forever -w start server.js
Here is a blog post about Hot Reloading for Node. It provides a github Node branch that you can use to replace your installation of Node to enable Hot Reloading.
From the blog:
var requestHandler = require('./myRequestHandler');
process.watchFile('./myRequestHandler', function () {
module.unCacheModule('./myRequestHandler');
requestHandler = require('./myRequestHandler');
}
var reqHandlerClosure = function (req, res) {
requestHandler.handle(req, res);
}
http.createServer(reqHandlerClosure).listen(8000);
Now, any time you modify myRequestHandler.js, the above code will notice and replace the local requestHandler with the new code. Any existing requests will continue to use the old code, while any new incoming requests will use the new code. All without shutting down the server, bouncing any requests, prematurely killing any requests, or even relying on an intelligent load balancer.
I am working on making a rather tiny node "thing" that is able to load/unload modules at-will (so, i.e. you could be able to restart part of your application without bringing the whole app down).
I am incorporating a (very stupid) dependency management, so that if you want to stop a module, all the modules that depends on that will be stopped too.
So far so good, but then I stumbled into the issue of how to reload a module. Apparently, one could just remove the module from the "require" cache and have the job done. Since I'm not keen to change directly the node source code, I came up with a very hacky-hack that is: search in the stack trace the last call to the "require" function, grab a reference to it's "cache" field and..well, delete the reference to the node:
var args = arguments
while(!args['1'] || !args['1'].cache) {
args = args.callee.caller.arguments
}
var cache = args['1'].cache
util.log('remove cache ' + moduleFullpathAndExt)
delete( cache[ moduleFullpathAndExt ] )
Even easier, actually:
var deleteCache = function(moduleFullpathAndExt) {
delete( require.cache[ moduleFullpathAndExt ] )
}
Apparently, this works just fine. I have absolutely no idea of what that arguments["1"] means, but it's doing its job. I believe that the node guys will implement a reload facility someday, so I guess that for now this solution is acceptable too.
(btw. my "thing" will be here: https://github.com/cheng81/wirez , go there in a couple of weeks and you should see what I'm talking about)
solution at:
http://github.com/shimondoodkin/node-hot-reload
notice that you have to take care by yourself of the references used.
that means if you did : var x=require('foo'); y=x;z=x.bar; and hot reloaded
it.
it means you have to replace the references stored in x, y and z. in the hot reaload callback function.
some people confuse hot reload with auto restart
my nodejs-autorestart module also has upstart integration to enable auto start on boot.
if you have a small app auto restart is fine, but when you have a large app hot reload is more suitable. simply because hot reload is faster.
Also I like my node-inflow module.
Here's a low tech method for use in Windows. Put this in a batch file called serve.bat:
#echo off
:serve
start /wait node.exe %*
goto :serve
Now instead of running node app.js from your cmd shell, run serve app.js.
This will open a new shell window running the server. The batch file will block (because of the /wait) until you close the shell window, at which point the original cmd shell will ask "Terminate batch job (Y/N)?" If you answer "N" then the server will be relaunched.
Each time you want to restart the server, close the server window and answer "N" in the cmd shell.
my app structure:
NodeAPP (folder)
|-- app (folder)
|-- all other file is here
|-- node_modules (folder)
|-- package.json
|-- server.js (my server file)
first install reload with this command:
npm install [-g] [--save-dev] reload
then change package.json:
"scripts": {
"start": "nodemon -e css,ejs,js,json --watch app"
}
now you must use reload in your server file:
var express = require('express');
var reload = require('reload');
var app = express();
app.set('port', process.env.PORT || 3000);
var server = app.listen(app.get('port'), function() {
console.log( 'server is running on port ' + app.get('port'));
});
reload(server, app);
and for last change, end of your response send this script:
<script src="/reload/reload.js"></script>
now start your app with this code:
npm start
You can do it with browser-refresh. Your node app restarts automatically, your result page in browser also refreshes automatically. Downside is that you have to put js snippet on generated page. Here's the repo for the working example.
const http = require('http');
const hostname = 'localhost';
const port = 3000;
const server = http.createServer((req, res) => {
res.statusCode = 200;
res.setHeader('Content-Type', 'text/html; charset=UTF-8');
res.write('Simple refresh!');
res.write(`<script src=${process.env.BROWSER_REFRESH_URL}></script>`);
res.end();
})
server.listen(port, hostname, () => {
console.log(`Server running at http://${hostname}:${port}/`);
if (process.send) {
process.send({ event: 'online', url: `http://${hostname}:${port}/` })
}
});
Not necessary to use nodemon or other tools like that. Just use capabilities of your IDE.
Probably best one is IntelliJ WebStorm with hot reload feature (automatic server and browser reload) for node.js.
I have tried pm2 : installation is easy and easy to use too; the result is satisfying. However, we have to take care of which edition of pm2 that we want. pm 2 runtime is the free edition, whereas pm2 plus and pm2 enterprise are not free.
As for Strongloop, my installation failed or was not complete, so I couldn't use it.
If your talking about server side NodeJS hot-reloading, lets say you wish to have an Javascript file on the server which has an express route described and you want this Javascript file to hot reload rather than the server re-starting on file change then razzle can do that.
An example of this is basic-server
https://github.com/jaredpalmer/razzle/tree/master/examples/basic-server
The file https://github.com/jaredpalmer/razzle/blob/master/examples/basic-server/src/server.js will hot-reload if it is changed and saved, the server does not re-start.
This means you can program a REST server which can hot-reload using this razzle.
it's quite simple to just do this yourself without any dependency... the built in file watcher have matured enough that it dose not sucks as much as before
you don't need any complicated child process to spawn/kill & pipe std to in/out... you just need a simple web worker, that's all! A web Worker is also what i would have used in browsers too... so stick to web techniques! worker will also log to the console
import { watch } from 'node:fs/promises'
import { Worker } from 'node:worker_threads'
let worker = new Worker('./app.js')
async function reloadOnChange (dir) {
const watcher = watch(dir, { recursive: true })
for await (const change of watcher) {
if (change.filename.endsWith('.js')) {
worker.terminate()
worker = new Worker('./app.js')
}
}
}
// All the folder to watch for
['./src', './lib', './test'].map(reloadOnChange)
this might not be the best solution where you use anything else other than javascript and do not depend on some build process.
Use this:
function reload_config(file) {
if (!(this instanceof reload_config))
return new reload_config(file);
var self = this;
self.path = path.resolve(file);
fs.watchFile(file, function(curr, prev) {
delete require.cache[self.path];
_.extend(self, require(file));
});
_.extend(self, require(file));
}
All you have to do now is:
var config = reload_config("./config");
And config will automatically get reloaded :)
loaddir is my solution for quick loading of a directory, recursively.
can return
{ 'path/to/file': 'fileContents...' }
or
{ path: { to: { file: 'fileContents'} } }
It has callback which will be called when the file is changed.
It handles situations where files are large enough that watch gets called before they're done writing.
I've been using it in projects for a year or so, and just recently added promises to it.
Help me battle test it!
https://github.com/danschumann/loaddir
You can use auto-reload to reload the module without shutdown the server.
install
npm install auto-reload
example
data.json
{ "name" : "Alan" }
test.js
var fs = require('fs');
var reload = require('auto-reload');
var data = reload('./data', 3000); // reload every 3 secs
// print data every sec
setInterval(function() {
console.log(data);
}, 1000);
// update data.json every 3 secs
setInterval(function() {
var data = '{ "name":"' + Math.random() + '" }';
fs.writeFile('./data.json', data);
}, 3000);
Result:
{ name: 'Alan' }
{ name: 'Alan' }
{ name: 'Alan' }
{ name: 'Alan' }
{ name: 'Alan' }
{ name: '0.8272748321760446' }
{ name: '0.8272748321760446' }
{ name: '0.8272748321760446' }
{ name: '0.07935990858823061' }
{ name: '0.07935990858823061' }
{ name: '0.07935990858823061' }
{ name: '0.20851597073487937' }
{ name: '0.20851597073487937' }
{ name: '0.20851597073487937' }
another simple solution is to use fs.readFile instead of using require
you can save a text file contaning a json object, and create a interval on the server to reload this object.
pros:
no need to use external libs
relevant for production (reloading config file on change)
easy to implement
cons:
you can't reload a module - just a json containing key-value data
For people using Vagrant and PHPStorm, file watcher is a faster approach
disable immediate sync of the files so you run the command only on save then create a scope for the *.js files and working directories and add this command
vagrant ssh -c "/var/www/gadelkareem.com/forever.sh restart"
where forever.sh is like
#!/bin/bash
cd /var/www/gadelkareem.com/ && forever $1 -l /var/www/gadelkareem.com/.tmp/log/forever.log -a app.js
I recently came to this question because the usual suspects were not working with linked packages. If you're like me and are taking advantage of npm link during development to effectively work on a project that is made up of many packages, it's important that changes that occur in dependencies trigger a reload as well.
After having tried node-mon and pm2, even following their instructions for additionally watching the node_modules folder, they still did not pick up changes. Although there are some custom solutions in the answers here, for something like this, a separate package is cleaner. I came across node-dev today and it works perfectly without any options or configuration.
From the Readme:
In contrast to tools like supervisor or nodemon it doesn't scan the filesystem for files to be watched. Instead it hooks into Node's require() function to watch only the files that have been actually required.
const cleanCache = (moduleId) => {
const module = require.cache[moduleId];
if (!module) {
return;
}
// 1. clean parent
if (module.parent) {
module.parent.children.splice(module.parent.children.indexOf(module), 1);
}
// 2. clean self
require.cache[moduleId] = null;
};