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This guide explains how to set up basic tools for working with JavaScript projects on your computer, specifically for working with Node.js (also called Node) and npm, so that you can run and modify 18F projects that use these tools. (People who use JavaScript have built many useful tools on top of JavaScript, and this guide explains the few that we use a lot at 18F; this doesn't cover the entire JavaScript ecosystem.)
We wrote this guide for people inside and outside 18F who want to set up their own development environments for contributing to our projects — or reusing and adapting these projects for their own purposes! Following these setup instructions doesn't require knowing how to code.
Note: this guide talks about both npm and nvm — one letter different, but different tools.
There are multiple ways to install Node, including through the binary downloads on nodejs.org, through Homebrew (brew) on OS X, or compiling it from source. We've found that the most useful way is to first install a tool called nvm (Node Version Manager), since nvm helps you install and use multiple versions of Node.
To install nvm, follow its installation instructions — running the install script should work fine.
Once you've installed nvm, you can use it by typing nvm on your command line. Now you can install a version of node. Let’s say your project calls for node v0.12.x (generally you can find this information under engines in the package.json at the root of the project).
You can issue the command nvm install 0.12 which will install the correct binary for node. You can see all of the node versions you have installed with nvm ls.
To use any of the versions of node you have installed, use the nvm use command. For example, if you wanted to use the v0.12 you just installed, you can say nvm use 0.12 and the version will be switched for you. You can confirm this by asking node for its version: node --version.
You can install any version of node this way. To see all the options, use nvm ls-remote.
Whoa, that’s a lot of nodes.
When you install Node, it comes with npm. npm is the de facto package manager for JavaScript. (If you're wondering, the team behind npm says it doesn't stand for Node Package Manager. It doesn’t matter what it stands for, it is just a useful tool and part of the JavaScript ecosystem.)
Take a look and see which version of npm you currently have installed. You can do this with a similar --version flag, like npm --version.
Now let’s say that you want to have a different version of npm installed for the version of node you’re using. npm is updatable through npm, so if you wanted version 2.11.3 of npm you would say npm install -g npm@2.11.3. Check your npm version after running this to make sure it worked.