Sandbox::https://github.com/mdn/webassembly-examples/blob/master/js-api-examples/global.html

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<!DOCTYPE html>

<head>

<title>WebAssembly Globals example</title>

</head>

<body>

const output = document.getElementById("output");

function assertEq(msg, got, expected) {

output.innerText += `Testing ${msg}: `;

if (got !== expected) {

output.innerText += `FAIL!\nGot: ${got}\nExpected: ${expected}\n`;

} else {

output.innerText += `SUCCESS! Got: ${got}\n`;

}

assertEq("WebAssembly.Global exists", typeof WebAssembly.Global, "function");

const global = new WebAssembly.Global({ value: "i32", mutable: true }, 0);

WebAssembly.instantiateStreaming(fetch("global.wasm"), { js: { global } })

.then(({ instance }) => {

assertEq("getting initial value from wasm", instance.exports.getGlobal(), 0);

global.value = 42;

assertEq("getting JS-updated value from wasm", instance.exports.getGlobal(), 42);

instance.exports.incGlobal();

assertEq("getting wasm-updated value from JS", global.value, 43);

});

</script>

</body>

</html>