如何从异步函数中获取数组的所有值

Question

I would like to download an XML file, convert it to JSON, Fill an array, send Values to an different API.

The things that work:

• Download mulitple XML files
• Convert it to JSON
• Fill an array with all the values

I can't get my head around the callback function. The code below will output:

Loading.. 34 done 34 done

Expected is Loading..34 done

function fillArray(callback) {
    console.log("Loading..");

    for (let i = 0;i < urlArray.length; i++){
        
        xml2json(urlArray[i], (json) => {
            
            let myArray = findProp(json, "value");
            
            for(let i = 0; i < myArray.length; i++){
                myArrlabel.push(myArray[i]);
               
            }
           
          callback();
        });
        
    }
    
    //return myArrlabel;
}

function useArray(){
    
    console.log(myArrlabel[15]);
    
    console.log("done");
    
}

fillArray(useArray);

The callback is inside the for loop, that's why I will get the above output. It could be a stupid question but I can't understand how to code this correctly.

edit.. added xml2json()

function xml2json(url, callback){
    http.get(url, (resp) => {
      let data = '';

      // A chunk of data has been recieved.
      resp.on("data", (chunk) => {
        data += chunk;
      });

      // The whole response has been received. Print out the result.
      resp.on("end", () => {

          let json = parser.toJson(data, options);
          callback(json);
      });

    }).on("error", (err) => {
      console.log("Error: " + err.message);
    });
}

Answer 1

尝试添加一个 var ，每次数据加载时都会像您的回调一样加 1