The global.set variable instruction sets the value of a global variable.

(module
  (import "console" "log" (func $log (param i32)))
  (global $var (mut i32) (i32.const 0))
  (func $main
    i32.const 10 ;; load a number onto the stack
    global.set $var ;; set the $var

    global.get $var ;; load $var onto the stack
    call $log ;; log the result
  )
  (start $main)
)

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

Syntax

global.set identifier

• global.set

  • : The global.set instruction type. Must always be included first.

  identifier

  • : An identifier for the global whose value you want to set. This can be one of the following:

    • name

      • : The identifying name set for the global when it was first initialized. This must begin with a $ symbol, for example $my_global.

      index

      • : The global’s index number, for example 0 for the first global in the Wasm script, 1 for the second, etc.

Type

[new_value] -> []

• new_value

  • : The new value set for the global. For the global.set instruction to succeed, the global must be mutable (the mut flag was set when it was declared), and the new_value must have the same data_type as the global.

Opcodes

InstructionBinary formatExample text => binaryglobal.set0x24global.set 0 => 0x24 0x00

Specifications

Browser compatibility

See also

• global

• global.get