Recently I saw a blog post which immediately caught my eye; "Roll your own Javascript runtime" written by the folks over at Deno. Given the proliferation of Javascript runtimes over the past few years, I thought "why not, I'll make my own Javascript runtime". The result is quite interesting, with ~100 lines of code we're able to run Javascript outside of a browser, and even send HTTP requests.

zjs requires cargo and rustc to be installed. The following versions are confirmed to work:

$ cargo -V
cargo 1.62.1 (a748cf5a3 2022-06-08)
$ rustc -V
rustc 1.62.1 (e092d0b6b 2022-07-16)

If you want to try out zjs for yourself, follow the steps below:

# Clone the repository
git clone git@github.com:JLCarveth/zjs.git

cd zjs

cargo build

Once compiled, a zjs binary will be available at target/debug/zjs. You can run the example file with the following command:

target/debug/zjs example.js

The following should be output to the console:

[out]: "Hello, zjs!"
[err]: "Uh oh... Something went wrong."
[err]: "Unable to read file" "./log.txt" {}
[out]: "Read from a file" "./log.txt" "contents:" "I can write to a file."
[out]: "Removing file" "./log.txt"
[out]: "Removed file"
[out]: "Sending a GET HTTP Request"
[out]: "[\"0439f6cd-9a1a-412b-973f-3b3ba56ea0f9\"]"