window.focus() makes a request to bring that window to the front (MDN). It returns undefined.
Pass the required arguments shown below. Check return values and browser support before you rely on the result.
Call window.focus. Start with this line.
focus() / window.focus()| Call | What it does |
|---|---|
focus() / window.focus() | Primary signature. |
window.focus(...) | Call with the arguments your case needs. |
Built into the browser. Call window.focus(...) (or the global focus(...)) — no import required.
focus() / window.focus()This member has no parameters beyond those shown in the signature.
| Return Value | Description |
|---|---|
| * | Always undefined |
focus()Request focus for the current window from a button click.
window.focus();
// same as: focus();
console.log("focus() called");
console.log("hasFocus:", document.hasFocus());window.focus(). No arguments.document.hasFocus() reports whether this document is focused.focus() always returns undefined.
const result = window.focus();
console.log(result); // undefined
console.log(typeof result); // "undefined"undefined.typeof prints "undefined".Open a child window, then request focus on that reference.
const popup = window.open("", "demo", "width=320,height=200");
if (popup) {
popup.document.write("Popup demo
");
popup.focus(); // request — may be blocked
console.log("Asked popup to focus");
} else {
console.log("Popup blocked");
}popup is a Window.popup.focus(). Asks the browser to raise that window.open returns null, show a message instead.element.focus()Window focus and element focus are different APIs.
window.focus(); // browsing window / tab
document.getElementById("name").focus(); // keyboard focus on a controlfocus EventReact when the user returns to the tab — often more useful than calling focus().
window.addEventListener("focus", () => {
console.log("Window gained focus");
});
window.addEventListener("blur", () => {
console.log("Window lost focus");
});
// Switch to another tab, then come back, to see both logs.focus and blur on window.blur fires.focus fires.Window.focus() is marked Baseline Widely available on MDN (since July 2015). Availability ≠ unrestricted focus stealing — user agents still limit when the request succeeds.
Request to bring a window to the front across modern browsers.
Bottom line: Safe to call. Do not build critical UX that requires stealing focus from other windows.
Read final computed CSS values on DOM elements.
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