What sets apart nest launch from node dist/main.js execution?

Question

What sets apart nest launch from node dist/main.js execution?

Working on a Nest project, I noticed that the "start" configuration in the package.json file is structured like this:

"start:dev": "nest start --watch",
"start": "node dist/main.js",

I am curious why the second line doesn't simply use "nest start" instead. Both commands seem to achieve the same outcome. According to the official documentation:

nest start ensures that the project has been built (similar to nest build) and then runs the compiled application using the node command in a streamlined manner.

It seems logical to always build the project before running it. So is there any particular reason not to use nest start? Could there be performance implications or other significant differences?

typescript nestjs package.json

Answer 1

Answer №1

While the @nestjs/cli is a useful tool for development purposes, its utility in production is limited. In most cases, there is no need to constantly recompile and restart the server using the --watch flag, live debugging with the --debug flag is usually unnecessary, and compiling code in production is best done beforehand to prevent sending source code instead of transpiled JS. With these considerations in mind, using nest start in production may not be necessary.

However, locally, it serves as a valuable tool for quickly restarting the server and generating files using the nest g command. While the nest start command does check if the project is already compiled by looking for a dist directory, it may not always ensure that the compilation is up to date. Adding the --watch flag can help trigger a recompile when needed.

Answer 2

While the @nestjs/cli is a useful tool for development purposes, its utility in production is limited. In most cases, there is no need to constantly recompile and restart the server using the --watch flag, live debugging with the --debug flag is usually unnecessary, and compiling code in production is best done beforehand to prevent sending source code instead of transpiled JS. With these considerations in mind, using nest start in production may not be necessary.

However, locally, it serves as a valuable tool for quickly restarting the server and generating files using the nest g command. While the nest start command does check if the project is already compiled by looking for a dist directory, it may not always ensure that the compilation is up to date. Adding the --watch flag can help trigger a recompile when needed.

Answer 3

Answer №2

According to the documentation provided by NestJS:

nest start simply makes sure that the project is built (similar to nest build), then it runs the node command in a convenient and portable way to execute the compiled application.

Essentially, it is just a simplified method for running production code, serving as a shortcut for two sequential commands: npm run build + npm run start:prod. You can use npm run start:prod if you are confident that the code has already been built, otherwise opt for nest start.

Answer 4

According to the documentation provided by NestJS:

nest start simply makes sure that the project is built (similar to nest build), then it runs the node command in a convenient and portable way to execute the compiled application.

Essentially, it is just a simplified method for running production code, serving as a shortcut for two sequential commands: npm run build + npm run start:prod. You can use npm run start:prod if you are confident that the code has already been built, otherwise opt for nest start.

Answer 5

Answer №3

Both of these commands have distinct purposes and can be applied in various scenarios.

"start": "node dist/main.js"

The "start" command is a direct way to execute your application by running the compiled JavaScript code located in your dist folder. This method skips the build process, assuming that your project has already been built and that the dist/main.js file exists. It is particularly suitable for production environments where everything is ready and tested, and you just need to start it quickly.

"start:dev": "nest start --watch" or "start": "nest start"

The "start:dev" command utilizes the Nest CLI to launch your application. With the nest start command, your project will be built before execution, which is beneficial during active development when constant code changes need immediate compilation from TypeScript to JavaScript. The optional --watch flag further enhances this functionality by monitoring file changes, automatically rebuilding, and restarting the app whenever modifications are detected.

The main distinction lies in the intended environment - production versus development. In production, speed is crucial, hence directly running the pre-built JavaScript is efficient. Whereas in development, automated building and restarting facilitate rapid iteration despite a slightly longer process.

In terms of performance, the impact is minimal. The build process is usually quick and occurs only once at startup (or upon file adjustments with --watch). The runtime efficiency of the app remains unaffected by the initialization method.

Answer 6

Both of these commands have distinct purposes and can be applied in various scenarios.

"start": "node dist/main.js"

The "start" command is a direct way to execute your application by running the compiled JavaScript code located in your dist folder. This method skips the build process, assuming that your project has already been built and that the dist/main.js file exists. It is particularly suitable for production environments where everything is ready and tested, and you just need to start it quickly.

"start:dev": "nest start --watch" or "start": "nest start"

The "start:dev" command utilizes the Nest CLI to launch your application. With the nest start command, your project will be built before execution, which is beneficial during active development when constant code changes need immediate compilation from TypeScript to JavaScript. The optional --watch flag further enhances this functionality by monitoring file changes, automatically rebuilding, and restarting the app whenever modifications are detected.

The main distinction lies in the intended environment - production versus development. In production, speed is crucial, hence directly running the pre-built JavaScript is efficient. Whereas in development, automated building and restarting facilitate rapid iteration despite a slightly longer process.

In terms of performance, the impact is minimal. The build process is usually quick and occurs only once at startup (or upon file adjustments with --watch). The runtime efficiency of the app remains unaffected by the initialization method.

What sets apart nest launch from node dist/main.js execution?

Answer №1

Answer №2

Answer №3

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