tasks.json

{
  // These tasks will run in order when initializing your CodeSandbox project.
  "setupTasks": [
    {
      "name": "Install Dependencies",
      "command": "npm install"
    }
  ],

  // These tasks can be run from CodeSandbox. Running one will open a log in the app.
  "tasks": {
    "start": {
      "name": "start",
      "command": "npm run start",
      "runAtStart": false
    },
    "server": {
      "name": "server",
      "command": "npm run server",
      "runAtStart": false
    },
    "client": {
      "name": "client",
      "command": "npm run client",
      "runAtStart": false
    },
    "dev": {
      "name": "dev",
      "command": "npm run dev",
      "runAtStart": true,
      "preview": {
        "port": 8000
      }
    },
    "heroku-postbuild": {
      "name": "heroku-postbuild",
      "command": "npm run heroku-postbuild",
      "runAtStart": false
    }
  }
}