Javascript chart.js 数据对象/数组

Question

i want to load in a data array for my chart like this:

data: chardata

I create a variable like this:

var chartdata = [];

i fill it with data from a function which should return an array but it returns an object

function getChartData(type) {
var chartdata = [];
console.log(typeof chartdata);
getDates(14).forEach(element => {
    var lastdate = new Date(element);
    lastdate.setHours(23);
    lastdate.setMinutes(59);
    lastdate.setSeconds(59);
    modlogRef.where("userName", "==", modname).where("action", "==", type).where("timestamp", ">=", element).where("timestamp", "<=", lastdate)
        .get()
        .then(function(querySnapshot) {
            chartdata.push(querySnapshot.size);
        })
        .catch(function(error) {
            console.log("Error getting documents: ", error);
        }); 
});
console.log(typeof chartdata);
return chartdata;

and when i look what type it is it says object put it shoud be a array? so when i return it to the chart and set data to chardata it fails because it is a object not an array? I even tried converting it to an array like this:

Object.values(chardata)

but that is just an empty array even if the object had values? What am i doing wrong? The error that i get is:

chart.js@2.8.0:7 Uncaught TypeError: Cannot read property 'skip' of undefined
    at ce (chart.js@2.8.0:7)
    at fe (chart.js@2.8.0:7)
    at me (chart.js@2.8.0:7)
    at ni.getElementsAtEventForMode (chart.js@2.8.0:7)
    at ni.handleEvent (chart.js@2.8.0:7)
    at ni.eventHandler (chart.js@2.8.0:7)
    at i (chart.js@2.8.0:7)
    at HTMLCanvasElement.Fe.<computed> (chart.js@2.8.0:7)

Answer 1

First in javascript an array is an object, to know if something is an array you should use Array.isArray(varName).

It looks like you get an empty array back because your query to get data returns nothing, I quickly pushed in a for loop some values to the array and it returns it fine so it must be your dataset which does not contain anything. Or your filters make it return nothing