FinalizationRegistry.prototype.unregister()

FinalizationRegistry 实例的 unregister() 方法从该 FinalizationRegistry 中取消注册目标值。

¥The unregister() method of FinalizationRegistry instances unregisters a target value from this FinalizationRegistry.

语法

¥Syntax

unregister(unregisterToken)

参数

¥Parameters

unregisterToken: 注册目标值时与 register() 方法一起使用的令牌。注册到相同 unregisterToken 的多个小区将一起取消注册。

返回值

¥Return value

一个布尔值，如果至少有一个单元未注册，则为 true；如果没有单元未注册，则为 false。

¥A boolean value that is true if at least one cell was unregistered and false if no cell was unregistered.

例外情况

¥Exceptions

TypeError: 如果 unregisterToken 不是对象或未注册符号，则抛出该异常。

描述

¥Description

当目标值被回收后，它就不再在注册表中注册。无需在清理回调中调用 unregister。仅当你未收到清理回调且不再需要接收时才调用 unregister。

¥When a target value has been reclaimed, it is no longer registered in the registry. There is no need to call unregister in your cleanup callback. Only call unregister if you haven't received a cleanup callback and no longer need to receive one.

示例

¥Examples

使用注销

¥Using unregister

此示例显示使用与取消注册令牌相同的对象来注册目标对象，然后通过 unregister 取消注册它：

¥This example shows registering a target object using that same object as the unregister token, then later unregistering it via unregister:

class Thingy {
  static #cleanup = (label) => {
    //               ^^^^^−−−−− held value
    console.error(
      `The "release" method was never called for the object with the label "${label}"`,
    );
  };
  #registry = new FinalizationRegistry(Thingy.#cleanup);

  /**

   * Constructs a `Thingy` instance.

   * Be sure to call `release` when you're done with it.

   *    * @param label A label for the `Thingy`.
   */
  constructor(label) {
    //                            vvvvv−−−−− held value
    this.#registry.register(this, label, this);
    //          target −−−−−^^^^         ^^^^−−−−− unregister token
  }

  /**

   * Releases resources held by this `Thingy` instance.
   */
  release() {
    this.#registry.unregister(this);
    //                        ^^^^−−−−− unregister token
  }
}

此示例显示使用不同的对象作为其取消注册令牌来注册目标对象：

¥This example shows registering a target object using a different object as its unregister token:

class Thingy {
  static #cleanup = (file) => {
    //               ^^^^−−−−− held value
    console.error(
      `The "release" method was never called for the "Thingy" for the file "${file.name}"`,
    );
  };
  #registry = new FinalizationRegistry(Thingy.#cleanup);
  #file;

  /**

   * Constructs a `Thingy` instance for the given file.

   * Be sure to call `release` when you're done with it.

   *    * @param filename The name of the file.
   */
  constructor(filename) {
    this.#file = File.open(filename);
    //                            vvvvv−−−−− held value
    this.#registry.register(this, label, this.#file);
    //          target −−−−−^^^^         ^^^^^^^^^^−−−−− unregister token
  }

  /**

   * Releases resources held by this `Thingy` instance.
   */
  release() {
    if (this.#file) {
      this.#registry.unregister(this.#file);
      //                        ^^^^^^^^^^−−−−− unregister token
      File.close(this.#file);
      this.#file = null;
    }
  }
}

规范

Specification
ECMAScript Language Specification # sec-finalization-registry.prototype.unregister

¥Specifications

浏览器兼容性

BCD tables only load in the browser

¥Browser compatibility

也可以看看

¥See also

FinalizationRegistry