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.wasm

WebAssembly Binary

Web & Development

WASM is a compiled WebAssembly module, not a standalone viewing document. A web app or compatible runtime loads it with required imports/features. Identify its JavaScript/runtime dependencies rather than executing arbitrary modules experimentally.

Main use
Provide compiled modules to a runtime
Data type
Executable / script
All sections, questions and sources

Content reviewed： · Editor：Kai

Opening steps

Choose your environment or purpose to see its steps.

WebAssembly runtime / development tools

Preserve the original and inspect a working copy in a compatible application.

  1. Identify the distributing app or development project.
  2. Inspect module imports/exports with development tools.
  3. Only execute when needed, using the specified environment and test data.
Inspect the received file and its requirements

Establish dependencies and settings before proceeding.

  1. Establish browser versus other-runtime targeting.
  2. Identify host code and required features.
  3. Inspect delivery MIME type, path and response content.

Menu labels and support vary by app, OS and version. Preserve the original before making changes.

Troubleshooting by symptom

  • Double-click fails: it needs its host application/runtime.
  • MIME error: inspect server delivery and application/wasm support.
  • Import error: inspect host-supplied functions/memory.
  • Validation fails in an older runtime: inspect feature support.

WASM → WAT / rebuild from source

  1. Use supported disassembly to WAT for inspection; plan migration from source/build configuration.
  2. Verify runtime, features, imports/exports and accompanying files.

WAT is not recovery of the original authored source; renaming does not produce JavaScript.

A module needs its host

The host supplies imports. Moving a browser-targeted module to another runtime need not work without matching APIs, memory and input/output conditions.

Source for these steps：Mozilla / MDN · WebAssembly concepts / Mozilla / MDN · Understanding WebAssembly text format

Worked example: checks before handoff

Example: for a web loading failure, check that the response is not an HTML error and that MIME/import requirements match.

Source for these steps：Mozilla / MDN · WebAssembly concepts / Mozilla / MDN · Understanding WebAssembly text format

Related-format differences

Related-format differences
Format / methodPurpose and preserved information
.wasmProvide compiled modules to a runtime
JS / WATJS is code in another language; WAT is WebAssembly text.
WASM → WAT / rebuild from sourceWAT is not recovery of the original authored source; renaming does not produce JavaScript.

Handling and security

Review runtime privileges and host capabilities; opacity is not proof of safety.

Questions and answers

Is WASM an image or video?

It is an executable module whose purpose depends on its host app.

Is it identical to WAT?

WAT is a textual representation and WASM binary.

Is WASM always standalone?

It can require host imports and accompanying JavaScript.

Format facts: name, steward and MIME type
Formal name
WebAssembly Binary
Steward / specification
Mozilla / MDN
MIME type
application/wasm

Primary and official sources