Promise.all不顯示數據

Question

我是承諾的新手，我想從類返回數據作爲承諾。我有兩個類，每個類都有兩個函數。我正在做的每個函數都是從類中返回一個承諾，但我無法執行promise.all。下面是代碼

Class1 

class TestClass { 

    firstPromise() { 
     return new Promise((resolve, reject) => { 
      resolve('return first promise') 
     }) 
    } 

    secondPromise() { 
     return new Promise((resolve, reject) => { 
      resolve('return second promise') 
     }) 
    } 
} 
module.exports.TestClass = TestClass; 

Class2 

class TestClass1 { 

    firstPromise() { 
     return new Promise((resolve, reject) => { 
      resolve('return first promise') 
     }) 
    } 

    secondPromise() { 
     return new Promise((resolve, reject) => { 
      resolve('return second promise') 
     }) 
    } 
} 
module.exports.TestClass1 = TestClass1; 

Main function 
    let data = req.body; 
    let test1Object; 
    let testObject; 
    let testParam; 
    let testParam1; 
    if (data.hasOwnProperty('param1')) { 
     test1Object = new test1.TestClass1(); 
     test1Object.firstPromise().then((data)=>{ 
      testParam1 = test1Object.secondPromise(); 
     }); 
    } 
    if (data.hasOwnProperty('param2')) { 
     testObject = new test.TestClass(); 
     testObject.firstPromise().then((data)=>{ 
      testParam = testObject.secondPromise() 
     }); 
    } 
    Promise.all([testParam,testParam1]).then((data)=>{ 
     console.log(data) 
    }); 

它顯示 [不確定的，不確定]

Answer 1

當你執行Promise.all()，承諾尚未解決，所以testParam和testParam1是undefined。我想你應該將第一個承諾testParam1：

testParam1 = test1Object.firstPromise().then(data => test1Object.secondPromise()); 

，同樣在第二到testParam：

testParam = testObject.firstPromise().then(data => testObject.secondPromise());