navigator.oscpu is a read-only Navigator property that returns a string identifying the operating system when the browser exposes it (MDN). Support is mainly Firefox / Gecko; elsewhere it is often missing.
Read the notes below before you rely on this property. Prefer feature detection when support is limited.
Use navigator.oscpu. Start with this line.
navigator.oscpu| Call | What it does |
|---|---|
navigator.oscpu | Primary signature. |
Built into the browser. Read navigator.oscpu on Navigator — no import required.
navigator.oscpu| Parameter | Description |
|---|---|
| "oscpu" in navigator | Required. Feature detect |
| Return Value | Description |
|---|---|
| * | The current value of navigator.oscpu. |
Check whether this browser exposes a usable oscpu string.
const supported =
"oscpu" in navigator && Boolean(navigator.oscpu);
console.log(supported ? "oscpu available" : "oscpu missing");in. Confirms the property exists on navigator.oscpu (MDN)MDN-style helper that surfaces the OS string when present.
function osInfo() {
if (!("oscpu" in navigator) || !navigator.oscpu) {
console.log("oscpu missing");
return;
}
console.log(navigator.oscpu);
}
osInfo();
// e.g. "Windows NT 6.0" in some Firefox setups (MDN)osInfo idea, without alert.Return a structured result instead of throwing or assuming support.
function readOscpu() {
if (!("oscpu" in navigator) || !navigator.oscpu) {
return { ok: false, reason: "unsupported" };
}
return { ok: true, value: String(navigator.oscpu) };
}
console.log(JSON.stringify(readOscpu(), null, 2));unsupported path. Common on Chromium/WebKit.ok: true lie about the OS.platformCompare the Firefox-oriented string with the wider platform property.
const oscpu =
"oscpu" in navigator && navigator.oscpu
? String(navigator.oscpu)
: "(missing)";
console.log("oscpu: " + oscpu);
console.log("platform: " + navigator.platform);
console.log("Neither is reliable for OS sniffing");(missing) when oscpu is absent.platform. Wider support; still coarse and spoofable.Show the teaching pattern: detect APIs, do not parse OS names.
function choosePath() {
// Bad: if (navigator.oscpu.includes("Windows")) { … }
// Good: test the capability you need
if ("serviceWorker" in navigator) {
return "can use service workers";
}
return "no service workers — use a fallback";
}
console.log(choosePath());
console.log(
"oscpu present: " +
Boolean("oscpu" in navigator && navigator.oscpu)
);"serviceWorker" in navigator is capability-based.oscpu only as context. Not as the decision maker.navigator.oscpu is not Baseline. Useful support is mainly Firefox / Gecko. Other engines often omit it — always feature-detect.
Expect a string in Firefox. Treat Chromium, Safari, Edge, and Opera as usually unsupported for this property.
Bottom line: Learning / Firefox demos only. Prefer feature detection (and wider hints like platform) instead of OS sniffing.
Learn how navigator.pdfViewerEnabled reports inline PDF viewing support.
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