Browser Support?

Node.js

Support since v8.0

What is wasm?

• Bytecode for the browser
• All major browser vendors agreed on format
• Browsers implement VM to run wasm in

What languages can be compiled to wasm?

• Support is growing fast!
• List of wasm languages

But what does that actually mean?

• Compile anything to the web
• Create npm packages out of any third party library
• Pick the right tool for the task (e.g. math)

Compilation example

C

                
                    int factorial(int n) {
                      if (n == 0)
                        return 1;
                      else
                        return n * factorial(n - 1);
                    }
                
                

Intermediate format

                
                    get_local 0
                    i64.eqz
                    if (result i64)
                        i64.const 1
                    else
                        get_local 0
                        get_local 0
                        i64.const 1
                        i64.sub
                        call 0
                        i64.mul
                    end
                
                

wasm binary format

                
                    20 00
                    50
                    04 7E
                    42 01
                    05
                    20 00
                    20 00
                    42 01
                    7D
                    10 00
                    7E
                    0B
                
                

Text representation (s-expr)

                
                    (module
                      (import "math" "exp" (func $exp (param f64) (result f64)))
                      (func (export "doubleExp") (param $0 f64) (result f64)
                        (f64.mul
                          (call $exp
                            (get_local $0)
                          )
                          (f64.const 2)
                        )
                      )
                    )
                
                

Limitations

Memory

• Only flat linear memory support
• No Garbage Collection except custom written
• Work in progress

DOM

• No DOM access from within wasm
• DOM API proposed for future version

GPU

• No GPU access
• Not planned right now
• So no blockchain mining in the browser :)
• And no heavy Machine Learning...

Types

How do we exchange other types?

• Other types we have to pass the reference and read it directly from memory
• We'll see that later

What is coming?

Garbage Collection

• Currently not supported
• Languages with GC compile it themselves
• Bad for binary size and efficiency

Host bindings

• Currently we have a very limited interface
• Add sharing of JS/DOM objects
• Create, call, manipulate and pass objects

Threads

• Shared access to memory and atomic operations
• No mechanism for creating threads
• Supplied by the host which will be Web Workers

Exception Handling

• No support so far
• Fairly challenging proposal (#2)
• Currently proposing a generic concept of events

Reference Types

• Currently minimal set of types
• Serialize more complex types to memory
• New "anyref" type that allows references to JS objects

And so much more...