What does " yarn build " command do? Are " npm build " and "yarn build" similar commands?

What does yarn build command do ? Are yarn build and npm build the same? If not what's the difference?

yarn build and npm build are not existing commands by default. I think you mean yarn run build or npm run build.

build is a command which can be specified in your package.json file on the scripts property. See the example below.

{
    "name": "mypackage",
    "version": "0.1.0",
    "scripts": {
       "build": "webpack --config webpack.dev.js"
    }
}

In this example, build is a shortcut for launching command webpack --config webpack.dev.js. You can use every keyword you want to define some shortcuts to launch commands.

And the only difference between the two commands it's the JS dependency manager you're using, yarn or npm.

More infos :

https://yarnpkg.com/lang/en/

https://www.npmjs.com/

"yarn build Bundles the app into static files for production."

npm stands for Node Package Manager. It was released back in 2010, beginning a new era in web development. Until then, the project dependencies were downloaded and managed manually. npm was the magic wand that pushed the Web to the next level.

Yarn stands for Yet Another Resource Negotiator. The Yarn package manager is an alternative to npm, released by Facebook in October 2016. The original goal of Yarn was to deal with npm drawbacks, such as performance and security issues. Yarn was quickly positioned as a safe, fast, and reliable JavaScript dependency management tool.

Comparing npm and Yarn Commands

npm init | yarn init: create a new package

npm run | yarn run: run a script defined in the package.json

npm test | yarn test: test a package

npm publish | yarn publish: publish a package

npm cache clean | yarn cache clean: remove all data from the cache folder

Yarn vs npm: Speed and Performance

While both managers offers caching mechanisms, Yarn seems to do it a bit better. By implementing a zero-install paradigm, as we’ll see in the features comparison section, it’s capable of installing packages almost in no time.

its the same i guess the real difference between yarn and npm is the performance and security that yarn provides.

yarn actually installing packages in parallelly and Npm only install one package at a time

And Yarn have more secure dependency.