.reduce() 在 javascript 中不返回数组

Question

I wrote a function that takes in parsed JSON from a XML request, it works when I use forEach() so I wanted to use reduce() to push what I could do with JS. What am I doing wrong?

forEach function:

function whatTemp48h(response){
var data;
data = response ;
var temp = [];
data.hourly.data.forEach(function(el,inx){
    temp.push(el.apparentTemperature)

})
console.log(temp)
return temp;
}

Reduce function:

function gimmeThaTemps(res){
return res.hourly.data.reduce(function(accu,el,c){
    accu.push(el.apparentTemperature);
    return accu;
},[]);
}

it doesent return anything when I use reduce. I am using an AJAX call to return some parsed JSON and im calling the AJAX function and sending it a call back.

function getWeather(lat,long, cb){
var xhr = new XMLHttpRequest();
var response;
  xhr.open('GET','https://api.darksky.net/forecast/'+api_KEY+'/'+lat+','+long,true);
xhr.onload = function() {
    // console.log(this.responseText)
    // console.log(JSON.parse(this.responseText));
    cb(JSON.parse(this.responseText));
};
xhr.onerror = function() {
console.log("Connection error");
};
xhr.send();
}

when I call I do

var reqReturn = getWeather(decodeMTL.lat,decodeMTL.long,gimmeThaTemps)

console.log(reqReturn);

Sorry for the newbish question but im still learning JS. Ps I have a XMLhttpprerequest node npm to run it in my command line.

Answer 1

A bit off-topic, what you are looking for is probably function map :

return res.hourly.data.map(function(el) { return el.apparentTemperature; });

Or with lambda:

return res.hourly.data.map(el => el.apparentTemperature);

Answer 2

My code is wrong. I was returning inside a callback, therefore it was returning nowhere!!!