From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:40:17 -0500 Subject: initial commit --- .../global_objects/weakref/deref/index.html | 69 ++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 files/zh-cn/web/javascript/reference/global_objects/weakref/deref/index.html (limited to 'files/zh-cn/web/javascript/reference/global_objects/weakref/deref/index.html') diff --git a/files/zh-cn/web/javascript/reference/global_objects/weakref/deref/index.html b/files/zh-cn/web/javascript/reference/global_objects/weakref/deref/index.html new file mode 100644 index 0000000000..9d9fdbdba1 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/weakref/deref/index.html @@ -0,0 +1,69 @@ +--- +title: WeakRef.prototype.deref() +slug: Web/JavaScript/Reference/Global_Objects/WeakRef/deref +translation_of: Web/JavaScript/Reference/Global_Objects/WeakRef/deref +--- +
{{JSRef}}
+ +
+ +
deref方法返回{{jsxref("WeakRef")}} 实例的目标对象,如果目标对象已被垃圾收集,则返回undefined
+ +

语法

+ +
obj = ref.deref();
+
+ +

返回值

+ +

返回WeakRef的目标对象,如果该对象已被垃圾收集,则返回undefined

+ +

说明

+ +

有关一些重要说明,请参阅{{jsxref("WeakRef")}}页面上的Notes on WeakRefs

+ +

例子

+ +

使用deref

+ +

有关完整示例,请参阅{{jsxref("WeakRef")}}页面的示例部分。

+ +
const tick = () => {
+  // Get the element from the weak reference, if it still exists
+  const element = this.ref.deref();
+  if (element) {
+    element.textContent = ++this.count;
+  } else {
+    // The element doesn't exist anymore
+    console.log("The element is gone.");
+    this.stop();
+    this.ref = null;
+  }
+};
+ +

规范

+ + + + + + + + + + + + +
规范
{{SpecName('WeakRefs', '#sec-weak-ref.prototype.deref', 'WeakRef.prototype.deref()')}}
+ +

浏览器兼容性

+ + + +

{{Compat("javascript.builtins.WeakRef.deref")}}

+ +

相关链接

+ + -- cgit v1.2.3-54-g00ecf