What is the difference between npm install and npm run build?

Question

What is the difference between npm install and npm run build?

I have noticed in my project that sometimes npm starts failing when npm install is performed, but, upon running npm run build, it works just fine.

How does the inner workings of these two targets namely install and run build differ?

Answer 1

NPM in 2019

npm build no longer exists. You must call npm run build now. More info below.

TLDR;

npm install: installs dependencies, then calls the install from the package.json scripts field.

npm run build: runs the build field from the package.json scripts field.

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NPM Scripts Field

https://docs.npmjs.com/misc/scripts

There are many things you can put into the npm package.json scripts field. Check out the documentation link above more above the lifecycle of the scripts - most have pre and post hooks that you can run scripts before/after install, publish, uninstall, test, start, stop, shrinkwrap, version.

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To Complicate Things

• npm install is not the same as npm run install
• npm install installs package.json dependencies, then runs the package.json scripts.install
  • (Essentially calls npm run install after dependencies are installed.
• npm run install only runs the package.json scripts.install, it will not install dependencies.
• npm build used to be a valid command (used to be the same as npm run build) but it no longer is; it is now an internal command. If you run it you'll get: npm WARN build npm build called with no arguments. Did you mean to npm run-script build? You can read more on the documentation: https://docs.npmjs.com/cli/build

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Extra Notes

There are still two top level commands that will run scripts, they are:

• npm start which is the same as npm run start
• npm test ==> npm run test