const: Wasm numeric instruction

The const numeric instruction is used to declare numbers.

Try it

(module
  (import "console" "log" (func $log (param i32)))
  (func $main

    i32.const 10 ;; load a number onto the stack
    call $log ;; log the number

  )
  (start $main)
)

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

Syntax

value_type.const

value_type

The type of value the instruction is being run on. The following types support const:

• i32
• i64
• f32
• f64
• v128

const

The const instruction. Must always be included after the value_type and a period (.).

Type

[] -> [output]

output

The value being pushed onto the stack:

• For a non-SIMD value_type, this will be a basic numeric value such as 3 or 3.5.
• For a SIMD value_type, this will be a v128 type followed by a SIMD value interpretation, for example i32x4 0x9 0xa 0xb 0xc.

Binary encoding

Specifications

• WebAssembly Core Specification