Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/WeakSet/add below:

WeakSet.prototype.add() - JavaScript | MDN

Baseline Widely available

WeakSet 实例的 add() 方法在该 WeakSet 对象的末尾追加一个新的对象。

const weakset1 = new WeakSet();
const object1 = {};

weakset1.add(object1);
console.log(weakset1.has(object1));
// Expected output: true

try {
  weakset1.add(1);
} catch (error) {
  console.log(error);
  // Expected output (Chrome): TypeError: Invalid value used in weak set
  // Expected output (Firefox): TypeError: WeakSet value must be an object, got 1
  // Expected output (Safari): TypeError: Attempted to add a non-object key to a WeakSet
}

value

必须是对象或非全局注册的符号。将要添加到 WeakSet 集合中的值。

该 WeakSet 对象。

TypeError

如果 value 不是一个对象或非全局注册的符号，则抛出该异常。

const ws = new WeakSet();

ws.add(window); // 将 window 对象添加到 WeakSet

ws.has(window); // true

// WeakSet 只接受对象作为参数
ws.add(1);
// Chrome 中的结果：“TypeError: Invalid value used in weak set”
// Firefox 中的结果：“TypeError: 1 is not a non-null object”

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4