Javascript array not initialized

问题

I have a problem with javascript array when passing into another object array. I have tried everything I came out on net, but nothing is working.

Problem is in line when fetching data from api on dataValues[dataValues.length] = (v.potroseno_tekucine);. Its working with labelValues. When I alert data in loop its ok, but when it needs to be processed it looks like its undefined. But when I, for example, alert(dataValues.length) before var data, its working ok.

$(document).ready(function () {
var ctx = document.getElementById("PodrumarstvoDetalji").getContext("2d");
var labelValues = [];
var dataValues = [];
$.ajax({
    url: root + "api/StatistikaApi/GetPodrumarstvoChart/?vinograd_id=10",// + $("#vinograd_id").val(),
    type: "Get",
    contentType: 'json',
    dataType: 'json',
    success: function (data) {
        $.each(data, function (k, v) {
            labelValues[labelValues.length] = v.opis;
            dataValues[dataValues.length] = (v.potroseno_tekucine);
        });
    },
    error: function (msg) { alert(msg); }
});
var data = {
    labels: labelValues,
    datasets: [
        {
            label: "My First dataset",
            fillColor: "rgba(220,220,220,0.2)",
            strokeColor: "rgba(220,220,220,1)",
            pointColor: "rgba(220,220,220,1)",
            pointStrokeColor: "#ddd",
            pointHighlightFill: "#ddd",
            pointHighlightStroke: "rgba(220,220,220,1)",
            data: dataValues
        }/*,
        {
            label: "My Second dataset",
            fillColor: "rgba(151,187,205,0.2)",
            strokeColor: "rgba(151,187,205,1)",
            pointColor: "rgba(151,187,205,1)",
            pointStrokeColor: "#ddd",
            pointHighlightFill: "#ddd",
            pointHighlightStroke: "rgba(151,187,205,1)",
            data: [28, 48, 40, 19, 86, 27, 90]
        }*/
    ]
};


var myLineChart = new Chart(ctx).Line(data);
});

Can anyone help me please? I have tried with push, slice, concat but nothing...

回答1:

Ajax calls are asynchronous... this mean the data will be set before getting any response from your ajax request.

In order to fix this, you need to create your data in the ajax success callback function:

$.ajax({
    success: function (data) {
        $.each(data, function (k, v) {
            labelValues.push(v.opis);
            dataValues.push(v.potroseno_tekucine);
        });
        var data2 = {
          labels: labelValues,
          //...
        };
        //Insert your logic here to handle data2
    }
});

来源：https://stackoverflow.com/questions/31415601/javascript-array-not-initialized