How can I run multiple npm scripts in parallel

Question

In my package json I have these two scripts      scripts          start-watch    nodemon run-babel index js        wp-server    webpack-dev-server         I have to run these 2 scripts in parallel everytime I start developing in Node js  The first thing I thought of was adding a third script like this    dev    npm run start-watch  amp  amp  npm run wp-server        but that will wait for start-watch to finish before running wp-server   How can I run these in parallel  Please keep in mind that I need to see the output of these commands  Also  if your solution involves a build tool  I d rather use gulp instead of grunt because I already use it in another project

User · Answer

In a package json in the parent folder    dev     cd api  amp  amp  start npm run start   amp   cd    client  amp  amp  start npm run start     this work in windows

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Simple node script to get you going without too much hassle  Using readline to combine outputs so the lines don t get mangled   const   spawn     require  child process    const readline   require  readline         spawn  npm     run    start-watch       spawn  npm     run    wp-server      forEach child   gt        readline createInterface           input  child stdout        on  line   console log        readline createInterface           input  child stderr         on  line   console log

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I have been using npm-run-all for some time  but I never got along with it  because the output of the command in watch mode doesn t work well together  For example  if I start create-react-app and jest in watch mode  I will only be able to see the output from the last command I ran  So most of the time  I was running all my commands manually     This is why  I implement my own lib  run-screen  It still very young project  from yesterday  p   but it might be worth to look at it  in your case it would be   run-screen  npm run start-watch   npm run wp-server    Then you press the numeric key 1 to see the output of wp-server and press 0 to see the output of start-watch

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Just add this npm script to the package json file in the root folder             quot scripts quot                  quot start quot    quot react-scripts start quot      or whatever else depends on your project      quot dev quot    quot  cd server  amp  amp  npm run start   amp   cd    client  amp  amp  npm run start  quot

User · Answer

npm-run-all --parallel task1 task2   edit   You need to have npm-run-all installed beforehand  Also check this page for other usage scenarios

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You can use one  amp  for parallel run script   dev    npm run start-watch  amp  npm run wp-server    Reference link

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I ran into problems with  amp  and    which exit statuses and error throwing  respectively   Other solutions want to run any task with a given name  like npm-run-all  which wasn t my use case   So I created npm-run-parallel that runs npm scripts asynchronously and reports back when they re done   So  for your scripts  it d be   npm-run-parallel wp-server start-watch

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I ve checked almost all solutions from above and only with npm-run-all I was able to solve all problems  Main advantage over all other solution is an ability to run script with arguments        test static-server    cross-env NODE ENV test node server testsServer js      test jest    cross-env NODE ENV test jest      test    run-p test static-server   test jest --       --      test coverage    npm run test -- --coverage      test watch    npm run test -- --watchAll          Note run-p is shortcut for npm-run-all --parallel   This allows me to run command with arguments like npm run test watch -- Something   EDIT   There is one more useful option for npm-run-all    -r  --race   - - - - - - - Set the flag to kill all tasks when a task                             finished with zero  This option is valid only                             with  parallel  option    Add -r to your npm-run-all script to kill all processes when one finished with code 0  This is especially useful when you run a HTTP server and another script that use the server      test    run-p -r test static-server   test jest --       --

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but that will wait for start-watch to finish before running wp-server   For that to work  you will have to use start on your command  Others have already illustrated but this is how it will work  your code below    quot dev quot    quot npm run start-watch  amp  amp  npm run wp-server quot   Should be     quot dev quot    quot  start npm run start-watch  amp  amp  start npm run wp-server quot   What this will do is  it will open a separate instance for each command and process them concurrently  which shouldn t be an issue as far as your initial issue is concerned  Why do I say so  It s because these instances both open automatically while you run only 1 statement  which is your initial goal

User · Answer

How about forking Another option to run multiple Node scripts is with a single Node script  which can fork many others  Forking is supported natively in Node  so it adds no dependencies and is cross-platform   Minimal example This would just run the scripts as-is and assume they re located in the parent script s directory     fork-minimal js - run with  node fork-minimal js  const childProcess   require  child process     let scripts     some-script js    some-other-script js    scripts forEach script   gt  childProcess fork script      Verbose example This would run the scripts with arguments and configured by the many available options     fork-verbose js - run with  node fork-verbose js  const childProcess   require  child process     let scripts                   path   some-script js           args    -some arg     some other arg            options   cwd        env   NODE ENV   development                             path   some-other-script js           args    -another arg     yet other arg            options   cwd    some where else   env   NODE ENV   development              let runningScripts       scripts forEach script   gt        let runningScript   childProcess fork script path  script args  script options          Optionally attach event listeners to the script    runningScript on  close        gt  console log  Time to die            runningScripts push runningScript      Keep a reference to the script for later use       Communicating with forked scripts Forking also has the added benefit that the parent script can receive events from the forked child processes as well as send back  A common example is for the parent script to kill its forked children   runningScripts forEach runningScript   gt  runningScript kill      For more available events and methods see the ChildProcess documentation

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I have a crossplatform solution without any additional modules  I was looking for something like a try catch block I could use both in the cmd exe and in the bash    The solution is command1    command2 which seems to work in both enviroments same  So the solution for the OP is    scripts        start-watch    nodemon run-babel index js      wp-server    webpack-dev-server        first command is for the cmd exe  second one is for the bash    dev     start npm run start-watch  amp  amp  start npm run wp-server      npm run start-watch  amp  npm run wp-server       start    npm run dev      Then simple npm start  and npm run dev  will work on all platforms

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npm install npm-run-all --save-dev   package json    scripts        start-watch             wp-server             dev    npm-run-all --parallel start-watch wp-server      More info  https   github com mysticatea npm-run-all blob master docs npm-run-all md

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If you re using an UNIX-like environment  just use  amp  as the separator     dev    npm run start-watch  amp  npm run wp-server    Otherwise if you re interested on a cross-platform solution  you could use npm-run-all  module    dev    npm-run-all --parallel start-watch wp-server

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You should use npm-run-all  or concurrently  parallelshell   because it has more control over starting and killing commands  The operators  amp     are bad ideas because you ll need to manually stop it after all tests are finished   This is an example for protractor testing through npm   scripts       webdriver-start      node modules protractor bin webdriver-manager update  amp  amp    node modules protractor bin webdriver-manager start      protractor      node modules protractor bin protractor   tests protractor conf js      http-server      node modules http-server bin http-server -a localhost -p 8000      test    npm-run-all -p -r webdriver-start http-server protractor      -p   Run commands in parallel   -r   Kill all commands when one of them finishes with an exit code of zero   Running npm run test will start Selenium driver  start http server  to serve you files  and run protractor tests  Once all tests are finished  it will close the http server and the selenium driver

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If you replace the double ampersand with a single ampersand  the scripts will run concurrently

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In my case I have two projects  one was UI and the other was API  and both have their own script in their respective package json files   So  here is what I did   npm run --prefix react start amp   npm run --prefix express start amp

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A better solution is to use  amp    dev    npm run start-watch  amp  npm run wp-server

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My solution is similar to Piittis   though I had some problems using Windows  So I had to validate for win32   const   spawn     require  child process     function logData data        console info  stdout    data        function runProcess target        let command    npm       if  process platform      win32             command    npm cmd      I shit you not           const myProcess   spawn command    run   target       npm run server      myProcess stdout on  data   logData       myProcess stderr on  data   logData            gt        runProcess  server       package json script     runProcess  client

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Use a package called concurrently   npm i concurrently --save-dev  Then setup your npm run dev task as so    dev    concurrently --kill-others   npm run start-watch     npm run wp-server

User · Answer

From windows cmd you can use start    dev    start npm run start-watch  amp  amp  start npm run wp-server    Every command launched this way starts in its own window

User · Answer

This worked for me    quot start-express quot    quot tsc  amp  amp  nodemon dist server server js quot    quot start-react quot    quot react-scripts start quot    quot start-both quot    quot npm -p -r run start-react  amp  amp  -p -r npm run start-express quot     Both client and server are written in typescript  The React app is created with create-react-app with the typescript template and is in the default src directory  Express is in the server directory and the entry file is server js typescript code and transpiled into js and is put in the dist directory   checkout my project for more info  https   github com nickjohngray staticbackeditor UPDATE  calling npm run dev  to start things off   quot server quot    quot tsc-watch --onSuccess   quot node   dist server index js  quot  quot    quot start-server-dev quot    quot npm run build-server-dev  amp  amp  node src server index js quot    quot client quot    quot webpack-dev-server --mode development --devtool inline-source-map --hot quot    quot dev quot    quot concurrently   quot npm run build-server-dev  quot     quot npm run server  quot    quot npm run client  quot  quot

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Quick Solution  In this case  I d say the best bet If this script is for a private module intended to run only on  nix-based machines  you can use the control operator for forking processes  which looks like this   amp   An example of doing this in a partial package json file        name    npm-scripts-forking-example      scripts          bundle    watchify -vd -p browserify-hmr index js -o bundle js        serve     http-server -c 1 -a localhost        serve-bundle    npm run bundle  amp  npm run serve  amp         You d then execute them both in parallel via npm run serve-bundle  You can enhance the scripts to output the pids of the forked process to a file like so    serve-bundle    npm run bundle  amp  echo         gt  build bundle pid  amp  amp  npm run serve  amp  echo         gt  build serve pid  amp  amp  npm run open-browser     Google something like bash control operator for forking to learn more on how it works  I ve also provided some further context regarding leveraging Unix techniques in Node projects below   Further Context RE  Unix Tools  amp  Node js  If you re not on Windows  Unix tools techniques often work well to achieve something with Node scripts because     Much of Node js lovingly imitates Unix principles You re on  nix  incl  OS X  and NPM is using a shell anyway   Modules for system tasks in Nodeland are also often abstractions or approximations of Unix tools  from fs to streams

[javascript] How can I run multiple npm scripts in parallel?

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