This is the first part in a series about introducing the Rust language to JavaScript developers. Here are all the chapters:

1. Tooling Ecosystem Overview
2. Variables and Data Types
3. Functions and Control Flow
4. Pattern Matching and Enums

I find it easier to understand something new if it was explained in terms of something I already know - I thought there might be others like me :)

Here’s the tl;dr version:

Tool	JavaScript	Rust
Version Manager	nvm	rustup
Package Manager	npm	Cargo
Package Registry	npmjs.com	crates.io
Package Manifest	package.json	Cargo.toml
Dependency Lockfile	package-lock.json	Cargo.lock
Task Runner	npm scripts, gulp etc	make, cargo-make
Live Reload	nodemon	cargo-watch
Linter	ESLint, TSLint, JSLint	Clippy
Formatter	Prettier	rustfmt
Dependency Vulnerability Checker	npm audit	cargo-audit

Setup

Rust is installed using the rustup command. rustup is similar to nvm in Node.js. You can use it to install and manage multiple versions of Rust and more.

Cargo

Installing Rust using rustup also installs Cargo similar to how installing Node.js also installs NPM. Cargo is Rust’s package manager and would feel very familiar if you’ve used NPM before.

Rust’s packages are called “crates”, and they’re downloaded from the crates.io registry similar to how NPM packages are downloaded from npmjs.com.

NPM while primarily a package manager, is also used as a task runner using the npm scripts feature. Cargo has builtin support for common tasks like running code, building code etc. Cargo has features like workspaces (similar to lerna), dependency overrides (similar to patch-package) out of the box. It is also a test runner (similar to mocha, jest etc), benchmark runner etc.

So basically, Cargo is NPM on steroids!

Project Setup

Creating a new project is done by running

$ cargo new hello_rust

This is somewhat similar to npm init. This creates a directory called “hello_rust” with the following files:

hello_rust
├── .git
├── .gitignore
├── Cargo.toml
└─┬ src
  └── main.rs

Cargo.toml

This is the package manifest file similar to package.json. The lock file (package-lock.json equivalent) is named Cargo.lock. Opening the Cargo.toml, you’ll see a familiar layout:

[package]
name = "hello_rust"
version = "0.1.0"
authors = ["sheshbabu"]
edition = "2018"

[dependencies]

The [package] table contains metadata like the crate name, author, keywords etc. The [dependencies] table is similar to the dependencies object in package.json. Cargo.toml also supports [dev-dependencies] similar to devDependencies.

Dependency Management

Installing a new dependency is done by manually editing the Cargo.toml file, adding the dependency under [dependencies] and running cargo build. For example, if we want to install the “serde” crate, we need to edit the Cargo.toml file as follows:

[package]
name = "hello_rust"
version = "0.1.0"
authors = ["sheshbabu"]
edition = "2018"

[dependencies]
+ serde = "1.0.106"

and run

$ cargo build

Similarly, to remove or update a dependency, we need to manually edit the Cargo.toml file and run cargo build. I was initially confused by the existence of the cargo install command but it turned out to be an equivalent of npm install -g.

If you want something similar to npm install, npm update or npm uninstall, you can install cargo-edit which enhances Cargo with cargo add, cargo rm and cargo upgrade subcommands.

You can also specify the dependency version using patterns similar to NPM.

Development tools

Task Runner

Cargo supports running common tasks like build, run, test etc. But if you want something similar to NPM scripts, you can use make or cargo-make

Live Reload

Nodemon is an essential tool for Node.js development - it watches for changes to files and automatically restarts the application. cargo-watch is the equivalent in Rust world.

Linter and Formatter

Rust has builtin linter called Clippy and formatter called rustfmt. They’re equivalent to ESLint and Prettier in JS ecosystem. Precommit hooks can be managed using cargo-husky.

Vulnerability Checking

Scanning for vulnerabilities in dependencies is done using cargo-audit and is very similar to npm audit.

Thanks for reading! Feel free to follow me in Twitter for more posts like this :)