WebAssembly.Instance
A WebAssembly.Instance
object is a stateful, executable instance of a WebAssembly.Module
. Instance
objects contain all the Exported WebAssembly functions that allow calling into WebAssembly code from JavaScript.
Constructor
WebAssembly.Instance()
-
Creates a new
Instance
object.
Instance properties
exports
-
Returns an object containing as its members all the functions exported from the WebAssembly module instance, to allow them to be accessed and used by JavaScript. Read-only.
Examples
Synchronously instantiating a WebAssembly module
The WebAssembly.Instance()
constructor function can be called to synchronously instantiate a given WebAssembly.Module
object, for example:
js
const importObject = {
imports: {
imported_func(arg) {
console.log(arg);
},
},
};
fetch("simple.wasm")
.then((response) => response.arrayBuffer())
.then((bytes) => {
const mod = new WebAssembly.Module(bytes);
const instance = new WebAssembly.Instance(mod, importObject);
instance.exports.exported_func();
});
The preferred way to get an Instance
is asynchronously, for example using the WebAssembly.instantiateStreaming()
function like this:
js
const importObject = {
imports: {
imported_func(arg) {
console.log(arg);
},
},
};
WebAssembly.instantiateStreaming(fetch("simple.wasm"), importObject).then(
(obj) => obj.instance.exports.exported_func()
);
This also demonstrates how the exports
property is used to access exported functions.
Specifications
Specification |
---|
WebAssembly JavaScript Interface # instances |
Browser compatibility
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