值
一個字串。可能的值為 "open"（彈窗正在從顯示狀態變為隱藏狀態）或 "closed"（彈窗正在從隱藏狀態變為顯示狀態）。
示例
js
const popover = document.getElementById("mypopover");
// …
popover.addEventListener("beforetoggle", (event) => {
if (event.oldState === "open") {
console.log("Popover is being hidden");
} else {
console.log("Popover is being shown");
}
});
規範
| 規範 |
|---|
| HTML # dom-toggleevent-oldstate |
瀏覽器相容性
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