我如何從JavaScript中的then（）返回值？如何使用Promise中的值異步更新AngularJS狀態
我有以下功能：
function getResult(){
var promise = _myService.getAge();
var getResultPromise = promise.then(function(age){
return age;
})
return getResultPromise; //How do i get the age (value) here? *see image*
}
或者如何將我在下面的$$狀態對象訪問的價值？
如何：
//The simple solution, this is how to use a Promise:
let _myService = {
getAge: function() {
return new Promise(function(resolve, reject) {
setTimeout(function() {
resolve(3)
}, 500);
})
}
};
function getResult() {
_myService.getAge().then(function(age) {
console.log(age);
});
}
getResult();
//OR, maybe closer to OP's intended implementation, put the value in an outer state:
let outerState = {
age: 0
};
setTimeout(function() {
console.log(outerState)
}, 450);
let _myService2 = {
getAge: function() {
return new Promise(function(resolve, reject) {
setTimeout(function() {
resolve(8)
}, 750);
})
}
};
function addAgeToOuterState() {
pState = new Promise(function(resolve, reject) {
_myService2.getAge().then(function(newAge) {
outerState.age = newAge;
resolve(outerState);
});
});
pState.then(function() {
console.log(outerState);
});
return pState;
}
addAgeToOuterState()
//for fun
.then(function(outer) {
console.log(outer); //state is still here
});
你不...你必須返回的承諾本身，然後使用。然後從那裏你訪問它調用你的函數。除非你使用像async/await這樣的東西，而這只是發生器上的語法糖，否則不可能從承諾中獲得價值。 – m0meni
你可以嘗試使用promise.all（）https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/all – Raj
@Raj沒有意義。他沒有回覆一系列承諾。 – m0meni