javascript - ES6 : console. 登录 WeakSet 给出

Question

为什么console.log将弱集显示为 <items unknown> ?

[13:37:11] [~] node
Welcome to Node.js v14.4.0.
Type ".help" for more information.
> let student1 = { name: 'James', age: 26 };
undefined
> let student2 = { name: 'Julia', age: 27 };
undefined
> const roster = new WeakSet([student1, student2]);
undefined
> console.log(roster);
WeakSet { <items unknown> }
undefined

上下文:我在 WeakSet 上遇到了以下示例在 ES6 中。

let student1 = { name: 'James', age: 26 };
let student2 = { name: 'Julia', age: 27 };
const roster = new WeakSet([student1, student2]);
console.log(roster);

该示例表明它应该打印

WeakSet {Object {name: 'Julia', age: 27}, Object {name: 'Richard', age: 31}}

但是在节点 v14.4.0 中它打印

WeakSet { <items unknown> }

Answer 1

node-js 团队认为很难正确实现它。
这是问题:https://github.com/nodejs/node/issues/19001
所以这意味着 WeakSet 正常工作但 console.log 将始终输出一个空的 WeakSet
如果您仍然想检查 WeakMap，您可以使用 utils 检查:

const { inspect } = require('util');
let student1 = { name: 'James', age: 26 };
let student2 = { name: 'Julia', age: 27 };
const weakSet = new WeakSet([student1, student2]);
console.log(inspect(weakSet, { showHidden: true }));