javascript - Promise - 嵌套函数不起作用

Question

我想知道为什么下面的代码不起作用，毕竟它只是嵌套函数:

var calculus = new Promise((resolve, reject) => (resolve) => resolve(3))

var calculus2 = new Promise((resolve, reject) => {
  () => resolve(4)
})

calculus.then((result) => console.log(result))
calculus2.then((result) => console.log(result))

任何提示都会很棒， 谢谢

Answer 1

您需要调用嵌套函数。

var calculus = new Promise((resolve, reject) => ((resolve) => resolve(3))(resolve))

calculus.then((result) => console.log(result))

如果你不想在最后重复(resolve)，你可以去掉嵌套函数的参数。

var calculus = new Promise((resolve, reject) => (() => resolve(3))())

calculus.then((result) => console.log(result))

无论哪种情况，嵌套函数都没有多大意义，你可以这样写:

var calculus = new Promise((resolve, reject) => resolve(3))

calculus.then((result) => console.log(result))