Code Completion 5 Challenges

JavaScript Execution Model: Contexts, Realms, Jobs & Agents — Code Completion

Practice execution-model concepts with small JavaScript completions.

Inspect the current function call stack.

javascript Your answer

function work() {
  return new Error().stack;
}
console.log(work());

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Create an independent Realm-like global using a browser frame.

javascript Your answer

const frame = document.createElement("iframe");
document.body.append(frame);
console.log(frame.contentWindow.Array === Array);

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Schedule a Promise reaction as a Job.

javascript Your answer

Promise.resolve(42).then(value => console.log(value));

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Read shared memory atomically.

javascript Your answer

const view = new Int32Array(new SharedArrayBuffer(4));
Atomics.store(view, 0, 9);
console.log(Atomics.load(view, 0));

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Preserve synchronous-before-job ordering.

javascript Your answer

const order = [];
Promise.resolve().then(() => order.push("job"));
order.push("sync");
setTimeout(() => console.log(order.join(",")), 0);
// output: sync,job

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