Rust and TypeScript: A comprehensive guide to their differences and integration

As your applications grow more complex, you benefit increasingly more from development tools that enable type safety and provide error checking. This is why languages such as TypeScript and Rust have grown in popularity: Their strict type checking and ability to catch errors during development results in a more pleasant development experience with cleaner code and fewer bugs in production.

This article explains how Rust and TypeScript compare: what makes them similar, where they differ, and when they can be used together.

Dynamic vs. static programming languages

Type safety in programming is used to enforce how data is used and manage data consistency, safety, and performance. For example, in a dynamically typed language like JavaScript, you are at risk of runtime type errors and unexpected behavior in more complex applications, as it gets harder to see the underlying type of a variable as systems grow in size. For example, you may try to perform arithmetic on a variable, not realizing it has taken a string type from a HTML input elsewhere in your code. Statically typed languages enforce type safety as they include compilers that catch potential issues during development. 

Developers working in both Rust and TypeScript will find their type systems familiar, but if you're used to JavaScript's loose typing, you may want to brush up on variable typing before you start working in typed languages.

What is TypeScript? 

TypeScript is a free and open source, statically typed superset of JavaScript. It was built by Microsoft to address common issues JavaScript developers faced when building large applications. It introduces a type system that reduces runtime errors and improves code maintainability and documentation by helping developers catch issues early in development.

TypeScript is converted to plain JavaScript during a build process that does all type checking and flags any issues it finds that ensures the resulting code adheres to the specified types. This process leverages an Abstract Syntax Tree (AST) that analyzes the types, then emits the code that matches the specified ECMAScript target version.

It is relatively easy to download and get started with TypeScript.

Technical details of TypeScript

TypeScript strengths

• Type safety: TypeScript offers optional static typing, which allows you to declare types explicitly or rely on inferred types. Static typing is a major improvement to JavaScript and helps to avoid runtime errors as they are flagged during the build process.

• Interfaces: In TypeScript, interfaces define the shape of an object and specify the types of properties it should have. Interfaces can enforce consistency across multiple objects and function parameters, supporting building a clearer domain model by mapping out the structure of backend data.

• Class composition: TypeScript makes it easier to implement class composition — classes that combine functionality rather than relying solely on inheritance. You can use interfaces to define contracts for classes, which enforce the methods and properties a class should implement. This allows classes to implement multiple interfaces, which makes your code more modular and easier to extend and maintain.

• Easier to learn than Rust: TypeScript is a relatively high-level language, making it simpler than other languages such as Rust or C. This means there is less of a learning curve and it is more accessible to web developers.

• TypeScript ecosystem: TypeScript is compatible with various build tools and frameworks (Webpack, Babel, and React, among others). There is also an extensive set of type definitions (DefinitelyTyped) for popular JavaScript libraries, which allows developers to leverage TypeScript for third-party code. On top of this, TypeScript is highly popular and has a thriving community of developers and blog articles to answer any questions or difficulties you may encounter with it. All JavaScript is also TypeScript, making the learning curve and toolset easier to learn if you’re already familiar with JavaScript.

TypeScript weaknesses

• No control over memory assignment: Unlike languages like Rust (which compiles to assembly) and allows fine-grained control over memory, TypeScript transpiles to JavaScript, so you rely on processor and memory optimizations in a JavaScript engine, which limits its use in performance-critical applications.

• Types are just annotations: TypeScript types are just compile-time annotations; this means when TypeScript is transpiled to JavaScript, all type information is removed. Types are therefore not enforced at runtime, allowing potential runtime type mismatches.

TypeScript use cases

TypeScript is best suited to large-scale applications, web development, and generally any projects where maintainability and scalability are critical. Type safety can reduce the risk of errors in any application that has complex business logic, and it's also beneficial to teams for improving collaboration and documentation.

Developer satisfaction

TypeScript consistently ranks highly in surveys among developers discussing trends and key aspects of languages. It is widely praised for balancing JavaScript's flexibility with its improved safety and tooling. It also tops the list of most-used programming languages consistently, and there are several high-profile projects that use it in production, including those by companies like Microsoft, Slack, and Asana.

What is Rust?

Rust is a modern, systems-level programming language created by Mozilla that focuses on safety, performance, and concurrency. Rust is designed to solve some challenges around systems programming, mainly ensuring memory safety without sacrificing speed. Rust enforces strict rules around memory ownership, eliminating common issues such as null pointer dereferencing and memory leaks at compile time.

To get started with Rust, simply download it and begin coding straight away.

Technical details of Rust

Rust strengths

• Arrays: Rust distinguishes between fixed arrays (defined with a set length at compile time) and dynamic arrays (vectors) managed in the heap, allowing for flexible memory usage and efficiency when handling arrays.

• Memory safety through ownership: Rust has an ownership system which prevents data races and memory leaks. It enforces strict rules for who can access data at any given time. Ownership automatically enforces cleanup after use.

• Controlled access with borrowing: This is a system that allows you to use a value temporarily without taking responsibility for its ownership (lifecycle, memory cleanup, or exclusive access). There are two types: immutable borrowing, which means multiple parts of the code can read a value without changing it, which prevents conflicts; and mutable borrowing, which means only one part of the code can modify a value at a time, ensuring those changes don't cause unexpected behavior. To ensure memory safety and correctness, the developer can’t borrow values as both immutable and mutable simultaneously. 

• Control flow with pattern matching: Rust allows developers to destructure and match complex data structures with ease, which can make the control flow more readable and reduce the need for complex if-else chains.

• Traits for modularity: Traits are similar to interfaces in TypeScript; by implementing traits, developers can make types follow specified behavior, which makes the code more reusable and flexible.

• Strict compiler: Rust has a strict compiler that enforces safety and performance checks; it catches many issues, making potential runtime errors visible at compile time.

• Memory safety and performance: Rust ensures memory safety without a garbage collector, making it faster and safer for low-level applications compared to languages with runtime memory management.

• Strong typing: Owing to explicit typing, ownership, and borrowing rules, advanced generics, and traits, types are “first-class citizens” in Rust, which means they play a fundamental role in how the language is designed, structured, and used.

• Error handling: Rust’s error handling is more explicit and enforces best practices out of the box. The compiler discourages a “happy path only” coding style, leading to stronger and more predictable code.

• Memory allocation: Rust's ownership system gives developers precise control over the memory allocation, which is great for performance-critical applications.

• Ecosystem and tooling: Rust’s ecosystem includes a robust package manager (Cargo), strong documentation, a very capable standard library (std), and community-driven resources, supporting streamlined development.

Weaknesses

• Complexity: Rust can be complex, especially for developers used to higher-level languages. Concepts such as ownership and borrowing can be challenging to understand.

• No direct DOM manipulation: Since it was not originally designed to be run on the web, Rust requires WebAssembly (WASM) to work in web environments, making it less flexible and adding complexity for web-based projects.

• Slower development: Rust's strict checks and compiler can slow down development. It often takes time to meet the compiler's strict requirements. Depending on the project, this can be seen as a weakness, for instance, not all projects have critical safety or performance requirements, where this could be seen as an acceptable trade-off.

Rust use cases

Rust is ideal for any application that requires high performance and security, such as operating systems, game engines, real-time applications, or any application where error handling and type safety are critical.

Developer satisfaction

Rust ranked first place for “most admired” on the most recent Stack Overflow survey. Rust has a welcoming community and lots of resources to help newcomers, such as Rust by Example and Rustlings for hands-on learning. A few high-profile companies use Rust, such as Discord for voice and video chat infrastructure; Dropbox for file synchronization; and Amazon (AWS), Netflix, and Stripe for critical payment infrastructure.

Rust vs. Javascript / TypeScript: Key comparisons

Rust vs. Javascript type systems

TypeScript has a more flexible type system than Rust; for instance, any can be used in TypeScript as an escape hatch from the type system when needed, although this is strongly advised against as it can result in avoidable errors. This concept is forbidden in Rust, which doesn't allow for "loose" typing, ensuring a more predictable codebase.

Rust replaces nulls with the Option type, which either holds a value or signifies its absence. This prevents null pointer errors and eliminates the need to guard against variables that might be undefined. Rust forces developers to explicitly handle optional values, leading to safer code. 

The Result type used for error handling explicitly indicates success or failure, enabling safe, predictable error management without exceptions. This approach encourages developers to handle errors at compile time.

Rust vs. JavaScript syntax comparison

Both languages borrow C-style syntax; however, Rust uses structs and traits, whereas TypeScript has objects and interfaces. Rust allows you to be more expressive in the syntax, and depending on the background, this may be more than the developer is used to thinking about, so in comparison, Typescript will be a “lighter” syntactic load.

Rust vs. TypeScript compiler

As mentioned above, Rust's compiler is strict; it uses the borrow checker to enforce memory allocation rules, which prevents data races, use-after-free errors and memory corruption errors, all common causes of security vulnerabilities. The strict checking can make development slower, but the trade-off allows for highly reliable and optimized code.

TypeScript’s compiler is more flexible, as it can allow dynamic types like any to speed up development if necessary. Although it's not officially recommended, allowing dynamic types does allow developers to keep features they like and discard others they don't. TypeScript only performs a subset of checks that the Rust compiler runs, which makes the local development loop much faster.

How to leverage Rust's performance and safety

Rust was primarily designed with safety in mind, particularly for handling memory; this is one of the most common security vulnerabilities in languages like C or C++. If you're starting out with Rust, you should make sure you leverage its features that enhance the following aspects of your application:

• Performance: Rust's system-level capabilities and lack of garbage collection make it significantly faster in performance-critical applications, in contrast to TypeScript, whose runtime management limits its performance in certain contexts.

• Mutability: Rust makes mutability explicit, so variables are immutable (unchangeable) by default and require a special mut keyword for modification. TypeScript, by contrast, allows variables to change more freely, which can lead to unpredictable behavior.

• Error prevention: Rust's opt-out safety features, such as the borrow checker, proactively prevent memory issues and data races. While TypeScript adds types, it is still more lenient, which can allow errors like null references to occur.

When to use Rust or TypeScript

When deploying TypeScript, a runtime environment like Node.js is required to execute the JavaScript output, which can add overhead, dependencies, and complexity. Rust, on the other hand, compiles to native machine code, so there is no need for a runtime.

Rust is much better in CPU-bound tasks, such as string operations, file handling, and system-level interactions, where its performance and memory efficiency outstrips TypeScript. Rust is good for applications in data processing, command line tools, or backend systems requiring heavy computation, whereas TypeScript is better suited to web-based applications for rapid development and is easier to learn.

With upcoming EU legislation holding companies financially responsible for any cybersecurity issues, it's important to make your applications as secure as possible. Using type-safe languages with enhanced debugging tools like Rust or TypeScript can make this easier by reducing exploitable bugs in your code.

Using Rust on the web

Sometimes you want to do traditionally "backend" tasks on the front end. Why?

• To avoid latency in sending data between client and server

• To allow apps to work offline by doing work on the client side

• To enforce data privacy (for example, in healthcare, so that sensitive user data doesn't leave the user's device)

If those tasks were computationally intensive, you could outsource them to Rust to run on the client for improved performance. Rust can be integrated into a web project with the use of WebAssembly, which allows Rust code to run on the web. This opens up possibilities for using Rust in your TypeScript projects, particularly for any compute-intensive tasks. You can create web assembly modules using Rust's wasm-pack tool and then import them into your project and use them like any other JavaScript module.

Rust's performance benefits are also making their way into other JavaScript and TypeScript tools; for instance, Next.js (a JavaScript framework) now uses a Rust-based transpilation and minification tool. These tools leverage Rust's speed and memory efficiency to improve build times.

Another way you can integrate the use of Rust is by packaging your Rust code into a Lambda function and then calling it for any resource-intensive operations in your TypeScript code. You can also compile Rust to WebAssembly for AWS Lambda@Edge, enabling Rust to handle CloudFront triggers efficiently in edge environments traditionally limited to Python and Node.js. We at Contentful compile Rust to WebAssembly for use with Fastly Compute providing us with a powerful option for our edge environments where performance is critical.

Statically type your composable content with Rust and TypeScript

Developers can leverage the strengths of both Rust and TypeScript to build efficient applications. By using TypeScript’s static typing on the front end, developers can reduce errors and improve code maintainability. 

At Contentful, we use Rust for code running at the edge early in the lifecycle of a request, where we need stronger guarantees than TypeScript can deliver. Paired with a composable content platform like Contentful, this approach provides an error-resistant environment for managing and delivering content-rich applications.

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