[英]Function returning before the result from a promise?
getShowPopup(fileName,zoneId) {
return this.getDataFromServer(fileName,zoneId).then((response) => {
return response;
});
}
const showPopup = this.Service.getShowPopup(fileName,this.id);
showPopup is assigned with an undefined value. showPopup 被分配了一个未定义的值。 On debugging, the getShowPopup method is returning value before the promise is executed.
在调试时,getShowPopup 方法在 promise 执行之前返回值。 How can I make this synchronous so that it waits for the response and then return the correct result.
我怎样才能使这个同步,以便它等待响应,然后返回正确的结果。
I think better approach is to make it like this:我认为更好的方法是让它像这样:
// it should return Promise
function getShowPopup(fileName,zoneId) {
return this.getDataFromServer(fileName,zoneId);
}
// and then when you want to get value from this api call
const showPopup = this.Service.getShowPopup(fileName,this.id)
.then(response => response)
.catch(error => console.log(error));
now showPopup const should have value.现在 showPopup const 应该有价值。 Other approach is to make function async
其他方法是使 function 异步
async function getShowPopup(fileName,zoneId) {
return this.getDataFromServer(fileName,zoneId);
}
and then you will only have to use key word await然后你只需要使用关键字等待
// but if api call returns error, it will not be caught so you should put this call in try catch block
const showPopup = await this.Service.getShowPopup(fileName, this.id);
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