nx/docs/shared/recipes/tips-n-tricks/wait-for-tasks.md

Wait for Tasks to Finish

There are a couple ways to ensure that a set up task has been run before you run a particular task.

The most common solution is to use the dependsOn property. This works regardless of what executor the task is using. Once the dependent tasks have completed, the primary task will start.

If you are using the @nx/js:node executor, you can also use the waitUntilTargets option of that executor. Once the dependent tasks emit something to the console, the primary task will start.

dependsOn

If you have a React app called store and a database project called db, you may want to run nx clean db before you run nx e2e store.

To set that up, edit the store app's project.json file:

{% tabs %} {% tab label="Version 16+" %}

{
  "targets": {
    "e2e": {
      "dependsOn": [
        {
          "projects": ["db"],
          "target": "clean"
        }
      ]
    }
  }
}

{% /tab %} {% tab label="Version < 16" %}

{
  "targets": {
    "clean-db": {
      // Workaround task
      "command": "nx clean db"
    },
    "e2e": {
      "dependsOn": ["clean-db"] // Run clean-db on this project
    }
  }
}

{% /tab %} {% /tabs %}

This will make it so that all you need to do is run nx e2e store and Nx will make sure that nx clean db is run first.

waitUntilTargets

If you have a Node api called api and a database project called db, you may want to run nx serve db any time you run nx serve api.

To set that up, edit the api app's project.json file:

{
  "targets": {
    "serve": {
      "executor": "@nx/js:node",
      "options": {
        "waitUntilTargets": ["db:serve"]
      }
    }
  }
}

With this configuration in place, if you run nx serve api, Nx will first run nx serve db. The nx serve api process will not be launched until nx serve db outputs something to the console. Then both processes will continue executing in parallel. When you kill the main process, both the db and api processes will be stopped.