Learn how to install WebAssembly locally to solve Exercism's exercises on your own machine
Many machines come pre-installed with Node.js or might have been installed previously, or as a dependency. So before we do anything, we should check if it's already installed:
If Node.js is installed, a version is displayed.
Write this version down.
If Node.js is not installed, an error will be written out.
Usually, something along the lines of
'node' is not recognised.
Browse to the Node.js website.
It will display two versions (if it detects your OS. Otherwise, select your OS first).
node -v version matches one of these, you're good.
If it doesn't, we recommend that you use Node.js LTS.
If you're worried upgrading might break something on your system, you can continue as if everything is fine;
we might not be able to provide support when something unexpected happens though.
There are a couple of ways to install Node.js:
Both options support Windows, macOS, and Linux. If you don't know what to do, using an installer is the easiest.
After the installer is done, or the package manager has completed, or the binary has been copied and the instructions have been followed, it's good to test if everything is alright.
The version should match the one on the website.
Note: It is important to open a new terminal window. Any open terminal windows might not have been refreshed after the installation completed. This means that the open terminals don't know that a new program was installed.
'node' is not recognised
If you've used the official installer, your
PATHshould have been automatically configured, but if your shell has trouble locating your globally installed modules — or if you build Node.js from source — update your
PATHto include the
On macOS and Linux you may accomplish this by adding the following to either
On Windows open the start menu and search for "environment variables". You'll need to edit the
PATHentry and add the path to the
npmbinaries here. Usually, these are found at
C:\Program Files\nodejs. If you browse here with your
File Explorer, you should find
Close any open terminals and open a new one.
Please follow these instructions to download the Exercism CLI for your OS.
Once the CLI is set up and configured, download the first exercise -
exercism download --exercise=hello-world --track=wasm
Each assignment then needs some tools to run the tests. They can be installed running this command within each assignment directory:
'<package>' is missing / cannot be found
If you see this after upgrading your exercise, welcome to npm 7. Delete
package-lock.jsonand re-run the command to resolve this.
If you're concerned about disk space and are okay installing another tool, take a look at pnpm, which ensure only one copy of each package-version is ever installed on disk.
In this case, run
pnpm install instead of
npm install, and everything should work as expected.
But what is npm and why does this work?
This works because
npmis a package manager that comes bundled with Node.js, which has been installed per the steps above. The
npmcommand looks for a
package.jsonfile, which is present in each assignment folder. This file lists the
"dependencies"above, which are then downloaded by
npmand placed into the
The scripts in the
package.jsonuse the binaries from the local
node_modulesfolder, and it's these scripts that are used to run the tests, as listed in the