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javascript - "Uncaught ReferenceError: chart is not defined"

转载 作者：行者123 更新时间：2023-11-29 15:40:20 27 4
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全部，

我正在使用以下 HTML/Javascript 代码:

<!doctype html>
<html>
<head>
    <script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
    <!-- google fonts from CDN -->
    <link href='http://fonts.googleapis.com/css?family=Open+Sans:400,300,600' rel='stylesheet' type='text/css'>
    <!-- highcharts -->
    <script src="http://code.highcharts.com/highcharts.js"></script>

    <style>
        html, body {
            width: 95%;
            margin: auto;
            font-family: 'Open Sans',sans-serif;
        }
        #chart_container {
            width:100%;
            height:500px;
        }
    </style>
</head>
<body>
    <h1>Live Data</h1>
    <div id="chart_container">

    </div>
</body>
<script type="text/javascript">
    $(document).ready(function() {
        chart = new Highcharts.Chart({
            chart: {
                renderTo: 'chart_container',
                defaultSeriesType: 'line',
                events: {
                    load: getBirds
                }
            },
            title: {
                text: 'DRHW Live Data Stream'
            },
            xAxis: {
                type: 'datetime',
                tickPixelInterval: 150,
                maxZoom: 20 * 1000
            },
            yAxis: {
                title: {
                    text: 'Count Observed'
                }
            },
            series: [
            ],
            legend: {
                layout: 'horiztonal',
                align: 'center'
            }
        });
        function getBirds() {
            var now = new Date();
            var et = now.getTime() / 1000; //PHP TS
            var st = et - 10; //30 seconds prior in PHP
            console.log(chart);
            if (chart.series.length > 0) {
                var series = chart.series[0];
                var length = series.length + 1;
                var shift = series.data.length > 20;
            }
            $.getJSON("https://path/to/json&callback=?", function(result) {
                var data = result.data;if (data.length == 0) {
                    return;
                } else {
                    additions = new Array();
                    for (i=0;i<data.length;i++) {
                        if (data[i].qstype != "1") {
                            species = data[i].answers[0]['answer'];
                            scode = species.substring(0,species.search(" - ")).trim()
                            count = (data[i].answers[1]['answer'] * 1);
                            newdata = new Object();
                            newdata['name'] = species;
                            newdata['count'] = count;
                            additions.push(newdata);
                        }
                    }
                    //now, for each addition, you need to loop through the existing data structures, and see if the thing exists.  if it does, add the data; if not, add the thing, then add the data.
                    var existingdata = chart.series;
                    for (i=0;i<additions.length;i++) {
                        isnewpoint = true;
                        for (j=0;j<existingdata.length;j++) {
                            if (existingdata[j].name == additions[i].name) {
                                isnewpoint = false
                                count = additions[i].count;
                                point = [now.getTime(),count];
                                chart.series[j].addPoint(point, true, shift);
                                shift = false; //this way, only one shift occurs - the first time through adding a new point to an existing data set. this will control against future shifting, either from other datapoints having new points added, 
                            }
                        }
                        if (isnewpoint) {
                            newseries = new Object();
                            count = additions[i].count;
                            newseries['name'] = additions[i].name;
                            for (j=0;j<length;j++) {
                                newseries['data'].push(0);
                            }
                            newseries['data'].push(count);
                            chart.series.push(newseries);
                        }
                    }
                    //we have now looped through and added a new data point to all species where new data was created in this pull.  We still need to add a new point to those that were not affected.
                    existingdata = chart.series;
                    for (i=0;i<existingdata.length;i++) {
                        getname = existingdata[i].name;
                        getlength = existingdata[i].data.length;
                        if (getlength<length) { //which we established earlier as one MORE than existed previously, prior to the addition
                            point = [now.getTime(),0]
                            chart.series[i].addPoint(point, true, shift);
                        }
                    }
                }
                setTimeout(getBirds,10000);
            });
        }
    });
</script>

</html>

我遇到的问题非常简单(但让我抓狂!)，并且在 js block 的早期。虽然我将变量“chart”定义为新的 Highcharts 图表，并且我将“getBirds”设置为加载后加载的函数，但 console.log 行告诉我图表未定义，下面的行它会抛出错误(Uncaught TypeError: Cannot read property 'series' of undefined)。

我检查了以下内容:

  1. Highcharts 引用资料 ( http://www.highcharts.com/docs/working-with-data/preprocessing-live-data )，其中建议的设置与我的类似；
  2. 我已经尝试在它自己的行上定义 chart 变量(这当然为我的 console.log 定义了图表，但没有定义所需的 chart.series在下一行)；
  3. 我已经研究了 stackoverflow 和其他有关可变范围的文档，但我认为根据我的研究我正在正确处理它。
  4. 我试过颠倒顺序 - 将 getBirds() 函数放在 chart 定义之上。

我很迷茫。非常感谢提供的任何帮助；提前致谢!

最佳答案

原因很可能是您无法在声明阶段引用变量。我猜 load 函数在声明时被调用。幸运的是，您可以在函数声明期间引用该对象。尝试以下代码块。

function getBirds(e) {
    var now = new Date(),
        et = now.getTime() / 1000, //PHP TS
        st = et - 10, //30 seconds prior in PHP
        chart = this;
    if (chart.series.length > 0) {

...在 var block 中声明 chart 变量。

关于javascript - "Uncaught ReferenceError: chart is not defined"，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/20166159/

27 4 0
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