Published Jul 19 2018
⚠️⚠️ JUST A FEW HOURS LEFT to JOIN THE 2023 BOOTCAMP ⚠️⚠️
In this post, I want to introduce a very powerful command that’s been available in npm starting version 5.2, released in July 2017: npx.
If you don’t want to install npm, you can install npx as a standalone package
npx
lets you run code built with Node and published through the npm registry.
Node developers used to publish most of the executable commands as global packages, in order for them to be in the path and executable immediately.
This was a pain because you could not really install different versions of the same command.
Running npx commandname
automatically finds the correct reference of the command inside the node_modules
folder of a project, without needing to know the exact path, and without requiring the package to be installed globally and in the user’s path.
There is another great feature of npm
, which is allowing to run commands without first installing them.
This is pretty useful, mostly because:
A typical demonstration of using npx
is through the cowsay
command. cowsay
will print a cow saying what you wrote in the command. For example:
cowsay "Hello"
will print
_______
< Hello >
-------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
Now, this if you have the cowsay
command globally installed from npm previously, otherwise you’ll get an error when you try to run the command.
npx
allows you to run that npm command without having it installed locally:
npx cowsay "Hello"
will do the job.
Now, this is a funny useless command. Other scenarios include:
vue
CLI tool to create new applications and run them: npx vue create my-vue-app
create-react-app
: npx create-react-app my-react-app
and many more.
Once downloaded, the downloaded code will be wiped.
Use the @
to specify the version, and combine that with the node
npm package:
npx node@6 -v #v6.14.3
npx node@8 -v #v8.11.3
This helps to avoid tools like nvm
or the other Node version management tools.
npx
does not limit you to the packages published on the npm registry.
You can run code that sits in a GitHub gist, for example:
npx https://gist.github.com/zkat/4bc19503fe9e9309e2bfaa2c58074d32
Of course, you need to be careful when running code that you do not control, as with great power comes great responsibility.
I wrote an entire book on this topic 👇
© 2023 Flavio Copes
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