Copy sign

(module
  (import "console" "log" (func $log (param f32)))
  (func $main
    ;; load `10` and a negative number onto the stack
    f32.const 10
    f32.const -2

    f32.copysign ;; copy just the sing bit from second to the first number
    call $log ;; log the result
  )
  (start $main)
)

const url = "{%wasm-url%}";
await WebAssembly.instantiateStreaming(fetch(url), { console });

;; load two numbers onto the stack
f32.const 10
f32.const -1

;; copy just the sign bit from the second number (-1) to the first (10)
f32.copysign

;; the top item on the stack will now be -10