return

return returns from a function.

  • If there are no values left on the stack, it returns nothing/void.
  • If there are the same amount of values left on the stack as specified in the function's type signature, it returns those values.
  • If there are more values than the function's return type specifies, then the topmost N values are returned, and the remaining values on the stack are discarded.

Try it

(module
  (func (export "get_90") (result i32)
    ;; load 10 onto the stack
    i32.const 10
    ;; load 90 onto the stack
    i32.const 90
    ;; return the second value (90); the first is discarded
    return
  )
)

const url = "{%wasm-url%}";
await WebAssembly.instantiateStreaming(fetch(url)).then((result) => {
  const { get_90 } = result.instance.exports;
  console.log(get_90());
  // Expected output: 90
});

Syntax

wat
f32.const 4.3
return
wat
i32.const 7
f32.const 4.3
return
Instruction Binary opcode
return 0x0f