在此页

• 句法
• 注意事项
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

unregister unregisters a target object from a FinalizationRegistry 实例。

句法

registry.unregister(unregisterToken);
					

参数

unregisterToken

The token used with the register method when registering the target object.

返回值

undefined .

注意事项

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

范例

Using unregister

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

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

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

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

规范
WeakRefs The definition of 'FinalizationRegistry.prototype.unregister' in that specification.

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
unregister	Chrome 84	Edge 84	Firefox 79	IE No	Opera No	Safari No	WebView Android 84	Chrome Android 84	Firefox Android No	Opera Android No	Safari iOS No	Samsung Internet Android No	nodejs 13.0.0 Disabled 13.0.0 Disabled Disabled From version 13.0.0: this feature is behind the --harmony-weak-refs runtime flag.

图例

完整支持

完整支持

不支持

不支持

用户必须明确启用此特征。

用户必须明确启用此特征。

另请参阅

• FinalizationRegistry

元数据

• 最后修改： Jul 13, 2020

相关话题

1. 标准内置对象
2. FinalizationRegistry
3. 方法
   1. FinalizationRegistry.prototype.register()
   2. FinalizationRegistry.prototype.unregister()
4. 继承：
5. Function
6. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
7. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
8. Object
9. 特性
   1. Object.prototype.__proto__
   2. Object.prototype.constructor
10. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.valueOf()
    12. Object.setPrototypeOf()