javascript - 不等待基于Promise的API回调(Not waiting for Promise based API callback)

Question

I can't get my API callback to execute before the rest of code.

(我无法在其余代码之前执行API回调。)

I always get the set element console logs, then the next step, then the callbacks.

(我总是得到set元素控制台日志，然后是下一步，然后是回调。)

Earlier versions of this pattern did not have a Promise in the actual callback.

(此模式的早期版本在实际的回调中没有Promise。)

I don't think it was needed but wanted to make sure that wasn't the issue.

(我认为这不是必需的，但想确保这不是问题。)

const xhrReqBase = function(req) {
    return new Promise(function(resolve, reject) {
        var xhr = new XMLHttpRequest();
        xhr.onreadystatechange = function() {
            if (xhr.readyState === 4 && xhr.status === 200) {
                resolve(xhr.responseText);
            } else if(xhr.readyState === 4 && xhr.status !== 200) {
                reject();
            }
        };
        xhr.open(req.method, req.url, true);
        xhr.send(JSON.stringify(req.requestBody));
    });
};

const xhrReq = async function(req) {
    let resp = await xhrReqBase(req);
    await req.callback(JSON.parse(resp));
};

const userReq = {
    method: "GET",
    url: "https://jsonplaceholder.typicode.com/users",
    callback: function(resp) {
        return new Promise(function(resolve, reject) {
            console.log("...callback");
            console.log(resp);    
            resolve();
        });
    }
};  

const getUsers = async function(valFromSetEle) {
    console.log("...a set element value:"+valFromSetEle);
    await xhrReq(userReq);
};

let aSet = new Set();
aSet.add(1);
aSet.add(2);
aSet.add(3);
//Either way below has the same result
//await aSet.forEach(getUsers);
//  OR
//await aSet.forEach(async function(valFromSetEle) {
//    await getUsers(valFromSetEle);
//});
console.log("...next step");

  ask by mikeatv translate from so

Answer 1

等待大神答复