One of the most powerful innovations of the Internet over the past few decades, WebAssembly is an open standard that defines a portable binary code format for executable programs. It is fast and portable in the true sense of the word. What makes it really useful is that most programming languages, including Rust and C++, target wasm for compilation. Rust is a very powerful language because of its efficient memory management. More than nine companies, including Dropbox, Coursera, Figma, NPM, Microsoft, Cloudflare, Facebook, Amazon, and Discord, use Rust for one thing or another. Seeing all the benefits of WebAssembly, we wondered, “Will WebAssembly replace JavaScript?”
This is one of the most frequently asked questions these days. So let’s do a simple comparison to see if WebAssembly can replace JS.
In this blog post, we’ll try to find out when JavaScript performs better than WASM, and when WASM performs better than JS. In addition, we’ll see how WASM works and why it is a good choice for network deployment.
Alternatives to JS
We’ve been using JavaScript as the only programming language, which is native to web browsers, and then we saw WebAssembly come along. But really what WebAssembly is. Let’s look at the definition of WASM.
WebAssembly, commonly known as WASM, is compact, fast, and portable code that runs on most browsers. WebAssembly is a binary instruction format, similar to Java bytecode. This code is not understood by us, but by a stack-based virtual machine. A stack-based virtual machine is a virtual machine that considers the operands of all instructions because they are on the stack.
We don’t normally write code in WASM. Wasm is a compilation target for many programming languages. Many languages compile their code into WASM to make it easier to transfer over the network for deployment purposes.
Another thing is that WASM is neither an assembly language nor built for a particular machine.
What it does is compile high-level languages and then run those web applications in a browser, much faster than JavaScript.
Some differences
First, we look at some of the benefits of JavaScripts, and then we’ll see what WebAssembly can do. In this way, we can get a good idea of their power.
JavaScript is dynamically typed, that is, types are related to run-time values, not named variables/fields/and so on. JavaScript, as we all know, is highly flexible. JS code is a human readable code.
On the other hand, WebAssembly is incredibly fast. It’s delivered in a small binary format, which actually makes it fast. It’s strongly typed.
Wasm work
Let’s take a look at how to use Wasm and how it works.
First, you write code for your web application in any language, i.e. Rust, C++, etc. You then compile it into WebAssembly bytecode, also known as a WASM file. The WASM file is then run in a web browser, where it becomes local machine code and is executed. It loads, parses, and executes much faster than JavaScript.
Binaries are lightweight, faster than text JS, and therefore faster to transfer and execute.
Performance comparison
So far, we’ve seen that WebAssembly is faster than JS. Let’s dig a little deeper and look at the performance differences between the two.
1.1.WebAssembly binaries download faster
JS needs to be parsed, compiled, and then optimized before executing the code, which is longer than WebAssembly’s fast binaries.
It’s easy to write code in JS, and it doesn’t compile ahead of time because it’s a dynamically typed language.
JavaScript still needs more time to do all the work it needs before it can execute the code.
2.WebAssembly manages memory manually
In WebAssembly, there is no garbage buildup and no performance impact.
3.WebAssembly reduces initial load time
Since WASM is statically typed, it does not need to infer the type at runtime. The main reason for the decrease in initial loading time is —
- It has a binary format
- It’s statically typed
- It performs the optimization task ahead of time when compiling the source code
JS, on the other hand, is tasked with converting text into a data structure called an abstract syntax tree, and then converting the syntax tree to binary format.
Wasm is three times better than JS in load time.
4.JavaScript tends to perform better during execution
Okay, this seems to contradict what we’ve been talking about. But here, we’re talking about two types of optimized code execution. Once fully optimized, WebAssembly executes code slower than JS in the browser.
conclusion
Now comes the time for the most contentious issues. Will WASM replace JS in the near future?
Actually, I don’t think so, because JS is still a very convenient option for many users to perform many tasks. It’s hard to believe that WASM can do all the things that JS can do now.