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JavaScript 中 Promise.resolve is not a constructor 错误

作者:迹忆客 最近更新:2022/12/02 浏览次数:

当我们尝试将 Promise.resolve() 方法与 new 运算符一起使用时,会出现“Promise.resolve is not a constructor”错误。 Promise.resolve() 方法不是构造函数,因此应该在没有 new 运算符的情况下使用它,例如 Promise.resolve('example')

下面是一个产生上述错误的示例代码

// ⛔️ Promise.resolve is not a constructor
const err = new Promise.resolve('example');

JavaScript Promise resolve is not a constructor

相反,我们不应该将 new 运算符与 Promise.resolve 方法一起使用。

// ✅ works
const resolved = Promise.resolve('example');

Promise.resolve 是一种方法,而不是构造函数。 该方法采用的唯一参数是要由 promise 解析的值。

Promise.resolve() 方法返回一个由提供的值解决的承诺。

请注意 ,与 Promise.resolve 方法相反,Promise() 是一个构造函数,用于包装尚不支持承诺的函数。

以下 2 个示例实现相同的结果:

const r1 = Promise.resolve('example');

const r2 = new Promise((resolve, reject) => {
  resolve('example');
});

这两个变量都存储了一个已实现的 promise ,但是,对于这个用例,Promise.resolve 方法为我们提供了比 Promise() 构造函数更直接和简洁的解决方案。

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