Highcharts无法使用装有ajax的数组进行渲染

Question

I just started using Highcharts but already got a problem. I want to fill my graph with data from an Ajax call but it just shows a blank graph.

First i want to show you how I get my data:

<?php

require_once("mysql_config.php");
$query = "SELECT temp FROM daten ORDER BY daten.id DESC LIMIT 0,6";

$answer = mysqli_query($mysqli,$query);
$row;

while($row = $answer->fetch_array()){
    echo $row['temp'] . ",";
}

?>

The output of this looks like: -20,0,0,7,0,0,100

And my AJAX Function:

function ajax(website, element, callback) {
    var http = null;
    var http = new XMLHttpRequest();
    var url = website;

    if(http!=null){
        http.open("POST",url,true);
        http.onreadystatechange = function(){

            if(http.readyState == 4){

                var text = http.responseText;
                callback(text, element);

            }

        }//Ende readychange

        http.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
        http.send();

    }//Ende if(http2!=null)

}//Ende Funktion

the callback is my create_chart function

function create_chart(rawdata, element){

newdata = rawdata.split(",");

//var newdata = [-20,0,0,7,0,0,100];

var chart = new Highcharts.Chart({
        chart: {
            type: 'line',
            renderTo: 'test'
        },
        title: {
            text: 'Testchart'
        },
        subtitle:{
            text: 'Subtitle'
        },
        xAxis: {
            categories: ['A','B','C','D','E','F','G']
        },
        yAxis: {
            title: {
                text: 'This is it'
            }
        },
        series: [{
            name: "Test",
            data: newdata
        }]
});

 }

The problem is, that it only draws a graph without data while using ajax but when I use an "prefilled" array (like the the one I commented out) it works fine.

Answer 1

newdata is a string and when you split it its pieces are strings.

"-20,0,0,7,0,0,100".split(",") = ["-20","0","0","7","0","0","100"]

Highcharts needs numbers, so after the split, parseInt them into numbers:

var rawdata = "-20,0,0,7,0,0,100";
var strdata = rawdata.split(",");
var newdata = []
for (var i = 0; i < strdata.length; i++)
{
   newdata.push(parseInt(strdata[i]));
} 

Fiddle here.