npm run start vs npm start with code examples

npm run start and npm start are two different commands that can be used to start a Node.js application. Both commands are used to start the application, but they work slightly differently.

npm start is the default command that is defined in the package.json file of a Node.js project. It is used to start the application without any additional arguments or options. The start script is defined in the scripts section of the package.json file, and it typically runs the main file of the application, such as index.js.

For example, if the main file of the application is index.js, the start script in the package.json file would look like this:

{
  "scripts": {
    "start": "node index.js"
  }
}

To start the application, you would simply run npm start in the command line.

npm run start works slightly differently. This command is used to run a script that is defined in the scripts section of the package.json file, but with additional arguments or options. For example, if you want to pass an environment variable to the application, you would use the run command.

For example, if you want to pass an environment variable NODE_ENV with a value of production to the application, you would use the following command:

npm run start -- --NODE_ENV=production

The run command also allows you to specify a different script to run, other than the default start script. For example, if you have a script called dev defined in the scripts section of the package.json file, you could run this script using npm run dev.

{
  "scripts": {
    "start": "node index.js",
    "dev": "nodemon index.js"
  }
}

In this example, running npm run dev would start the application using the nodemon tool, which automatically restarts the application whenever a change is made to the code.

In conclusion, npm start is the default command that runs the main file of the application, while npm run start allows you to run a script with additional arguments or options, and also allows you to specify a different script to run other than the default one.

In addition to npm start and npm run start, there are several other commands that are commonly used when working with Node.js applications.

One of these commands is npm test. This command is used to run test scripts that have been defined in the scripts section of the package.json file. These test scripts are typically used to automatically test the application and ensure that it is working correctly. There are several popular testing frameworks for Node.js, such as Mocha, Jest and Jasmine, that can be used to write and run test scripts.

Another useful command is npm install. This command is used to install the dependencies that are defined in the dependencies and devDependencies sections of the package.json file. These dependencies are typically libraries and modules that the application requires in order to function properly.

npm run build command is used to build the application. It runs the scripts defined in the package.json file that are associated with building the application. This command is common in production environments where the application needs to be built and optimized for performance.

npm run lint is a command used to lint the code, which checks for code style, syntax and other potential issues. This command runs the script associated with linting the code, which is useful for finding potential bugs and ensuring code quality.

npm run watch is a command used to watch the files for changes and re-build the application or re-run the tests automatically. This command is useful during development as it saves the time of running the command every time the code is changed.

These are just a few examples of the many commands that are available when working with Node.js applications. Each command serves a specific purpose and can be used to automate different tasks related to the development, testing and deployment of the application.

Popular questions

1. What is the difference between npm start and npm run start?

• npm start is the default command that runs the main file of the application, while npm run start allows you to run a script with additional arguments or options, and also allows you to specify a different script to run other than the default one.

2. How is the start script defined in the package.json file?

• The start script is defined in the scripts section of the package.json file and it typically runs the main file of the application, such as index.js. For example, if the main file of the application is index.js, the start script in the package.json file would look like this:

{
  "scripts": {
    "start": "node index.js"
  }
}

3. Can you pass arguments or options to the application when using npm start?

• No, npm start runs the default start script without any additional arguments or options. To pass arguments or options to the application, npm run start command should be used.

4. Can you run a different script than the default start script using npm start?

• No, npm start runs the default start script defined in the package.json file. To run a different script, npm run [script-name] command should be used.

5. What command is used to run test scripts for a Node.js application?

• The command npm test is used to run test scripts for a Node.js application. These test scripts are typically used to automatically test the application and ensure that it is working correctly.

Tag

Nodejs