Clarification for the memory.copy instruction

[Nosfy01]

MDN URL

https://developer.mozilla.org/en-US/docs/WebAssembly/Reference/Memory/Copy

What specific section or headline is this issue about?

Syntax

What information was incorrect, unhelpful, or incomplete?

The code samples seem to omit that the memory.copy instruction needs both a source and destination memory (unless of course their is only memory 0).

(memory.copy (memory $memoryName) (i32.const 50) (i32.const 100) (i32.const 25))

In this example the source memory used will be memory 0 and $memoryName will be the destination.

What did you expect to see?

(memory.copy (memory $destinationMemory) (memory $sourceMemory) (i32.const 50) (i32.const 100) (i32.const 25))

Do you have any supporting links, references, or citations?

No response

Do you have anything more you want to share?

My only source is my experimentation with compiled WebAssembly text format.
This is my first time suggesting an improvement, if my understanding of this topic is wrong or incomplete please let me know.

MDN metadata

Page report details

• Folder: en-us/webassembly/reference/memory/copy
• MDN URL: https://developer.mozilla.org/en-US/docs/WebAssembly/Reference/Memory/Copy
• GitHub URL: https://github.com/mdn/content/blob/main/files/en-us/webassembly/reference/memory/copy/index.md
• Last commit: d47940f
• Document last modified: 2025-04-13T06:53:10.000Z