node.js / promises /错误消息：…不是函数

Question

我正在尝试运行一个简单的2文件node.js项目。项目正在运行问题，并显示错误消息“ TypeError：steamBroccoli不是函数”。我从steamBroccoli（）中删除了大括号-它起作用了，该项目顺利运行。但是我不知道它是怎么运行的，也不知道为什么它指出了这个问题，因为steamBroccoli是一个函数。

library.js

let cookBeans = () => {
return new Promise ((resolve, reject) => {
 setTimeout(()=>{
   resolve('beans')
 }, 1000)
})
}

let steamBroccoli = () => {
return new Promise ((resolve, reject) => {
 setTimeout(()=>{
   resolve('broccoli')
 }, 1000)
})
}

let cookRice = () => {
return new Promise ((resolve, reject) => {
 setTimeout(()=>{
   resolve('rice')
 }, 1000)
})
}

let bakeChicken = () => {
return new Promise ((resolve, reject) => {
 setTimeout(()=>{
   resolve('chicken')
 }, 1000)
})
}

module.exports = {cookBeans, steamBroccoli, cookRice, bakeChicken}

let {cookBeans, steamBroccoli, cookRice, bakeChicken} = require('./library.js')

async function serveDinner(){
  const vegetablePromise = steamBroccoli(); // If I remove the braces  - The error disappear and the code works.  
  const starchPromise = cookRice();
  const proteinPromise = bakeChicken();
  const sidePromise = cookBeans();
  console.log(`Dinner is served. We're having ${await vegetablePromise}, ${await starchPromise}, ${await proteinPromise}, and ${await sidePromise}.`)
}
serveDinner();

Answer 1

您的示例代码有效！由于您使用的是箭头功能，因此可以重构您的诺言以删除一些样板代码。

const steamBroccoli = () => new Promise((resolve) => {
  setTimeout(() => resolve('broccoli'), 1000);
});