WebAssembly.instantiate()

Syntax

Primary overload taking wasm binary code

Promise<ResultObject> WebAssembly.instantiate(bufferSource, importObject);

Parameters

bufferSource

.wasm typed array ArrayBuffer.

importObject Optional

WebAssembly.Memory . . WebAssembly.LinkError .

Return value

ResultObject Promise :

• module: WebAssembly WebAssembly.Module . Module postMessage() cached in IndexedDB .
• instance: Exported WebAssembly functions WebAssembly.Instance .

Exceptions

• TypeError .
• promise WebAssembly.CompileError, WebAssembly.LinkError WebAssembly.RuntimeError reject.

Secondary overload taking a module object instance

Promise<WebAssembly.Instance> WebAssembly.instantiate(module, importObject);

Parameters

module

WebAssembly.Module .

importObject Optional

WebAssembly.Memory . module . WebAssembly.LinkError .

Return value

A Promise that resolves to an WebAssembly.Instance object.

Exceptions

• TypeError .
• If the operation fails, the promise rejects with a WebAssembly.CompileError, WebAssembly.LinkError, or WebAssembly.RuntimeError, depending on the cause of the failure. promise WebAssembly.CompileError, WebAssembly.LinkError WebAssembly.RuntimeError reject.

Examples

Note: instantiate() WebAssembly.instantiateStreaming () .

First overload example

fetch WebAssembly WebAssembly.instantiate () JavaScript WebAssembly . Instance Exported WebAssembly function .

var importObject = {
  imports: {
    imported_func: function (arg) {
      console.log(arg);
    },
  },
};

fetch("simple.wasm")
  .then((response) => response.arrayBuffer())
  .then((bytes) => WebAssembly.instantiate(bytes, importObject))
  .then((result) => result.instance.exports.exported_func());

Second overload example

(GitHub index-compile.html ). WebAssembly.compileStreaming () simple.wasm postMessage() worker .

var worker = new Worker("wasm_worker.js");

WebAssembly.compileStreaming(fetch("simple.wasm")).then((mod) =>
  worker.postMessage(mod),
);

(wasm_worker.js ) . WebAssembly.instantiate () .

var importObject = {
  imports: {
    imported_func: function (arg) {
      console.log(arg);
    },
  },
};

onmessage = function (e) {
  console.log("module received from main thread");
  var mod = e.data;

  WebAssembly.instantiate(mod, importObject).then(function (instance) {
    instance.exports.exported_func();
  });
};

See also

• WebAssembly overview page
• WebAssembly concepts
• Using the WebAssembly JavaScript API