npm-start

View documentation for the original command

$ tldr npm run

npm start

The `npm start` command is a crucial part of the Node.js development workflow, typically used to launch a Node.js application as defined in its `package.json` file. It executes the script specified in the `start` property within the `package.json`'s `scripts` section. This script often involves commands to initiate the application, such as running the main JavaScript file (e.g., `node index.js`), starting a development server, or building production assets using tools like Webpack or Parcel. The specific action performed depends entirely on the script defined in the `package.json` file.

By convention, `npm start` provides a standard way to initiate applications without the need for users to know the exact command required. This standardization promotes consistency and simplifies the process of running Node.js projects across different environments and setups. Developers can easily run a project using a simple command, as the project can have complex instructions inside its start script. The absence of a `start` script in `package.json` will result in npm displaying an error message. It's a fundamental command for both development and deployment.

The behavior of `npm start` is entirely dependent on the `start` script defined in the `package.json` file. If the `start` script is missing or invalid, the command will fail or produce unexpected results.

If npm is unable to find the start script specified or if the command fails, npm will terminate with an error.

The `start` script within `package.json` is a shell command. It is not necessarily just `node index.js`. It can include more complex commands like building assets, setting environment variables, or even running multiple commands sequentially or concurrently using tools like `npm-run-all` or `concurrently`.

If the `npm start` script exits with a non-zero exit code, npm will report an error. This is useful for detecting failures during application startup. You can use `npm config set loglevel=verbose` to increase verbosity in the output.

The `npm start` command emerged alongside the Node Package Manager (npm) as a way to standardize the execution of Node.js applications. As Node.js gained popularity, the need for a consistent way to run projects became apparent. The `scripts` section in `package.json`, including the `start` command, was introduced to address this need, providing a convention for defining and executing application-specific tasks.

npm run(1), package.json(5)