在带有回调的外部库中获取异步 function 以同步工作

Question

I am using a library call to connect to my vendor. The libary call requires a callback in the call. Without a callback in the function, I can easily make this synchronous. With the Callback, everything I do is stuck in the callback and never bubbles it way out.

I have literally tried 100 different ways to get this to work.

function removeFromDNC(emailAddress, accessToken_in) 
{
    return new Promise( function(resolve, reject) 
    {
        try{
            const options = 
            {   
                auth: {
                accessToken: accessToken_in
                }
                , soapEndpoint: 'https://webservice.XXX.exacttarget.com/Service.asmx' 
            };

            var co = {
                "CustomerKey": "DNC",
                "Keys":[
                    {"Key":{"Name":"Email Address","Value": emailAddress}}]
            };

            var uo = {
                SaveOptions: [{"SaveOption":{PropertyName:"DataExtensionObject",SaveAction:"Delete"}}]
              };


            const soapClient = new FuelSoap(options); 
           //again, I don't control the structure of the next call.          
            let res = soapClient.delete('DataExtensionObject', co, uo, async function( err, response ) {
                if ( err ) {
                    // I can get here, but my reject, or if I use return, does nothing
                    
                     reject();
                }else{
                    // I can get here, but my reject, or if I use return, does nothing
                    resolve();
                }
            });
            console.log("res value " + res);  // undefined - of course
            
        }catch(err){
            console.log("ALERT:  Bad response back for removeFromDNC for email: " + emailAddress + " error: " + err);
            console.log("removeFromDNC promise fulfilled in catch");
            reject();  
        }
    });   
}

Answer 1

Both methods resolve and reject expect parameters, which are res and err in your case.
As far as removeFromDNC returns a Promise instance, you should call it using either async/await syntax:

const res = await removeFromDNC(...);

or chaining then/catch calls:

removeFromDNC(...)
  .then((res) => { ... })    // resolve
  .catch((err) => { ... })   // reject

EDIT:
If you want to avoid usage of callbacks inside removeFromDNC , consider promisifying of soapClient.delete call. Refer to util.promisify() if you working in Node.js or use own implementation.

Here is the example for demonstration:

 const promisify = (fun) => (...args) => { return new Promise((resolve, reject) => { fun(...args, (err, result) => { if(err) reject(err); else resolve(result); }) }) } const soapClient = { delete: (value, cb) => { setTimeout(() => cb(null, value), 10); } }; async function removeFromDNC(emailAddress, accessToken_in) { const soapDelete = promisify(soapClient.delete.bind(soapClient)); const res = await soapDelete('Soap Responce'); //You can use res here return res; } removeFromDNC().then(res => console.log(res))