无法设置 Javascript 对象属性

由于某种原因，我无法设置以文字形式创建的Javascript对象的属性。使用 PHP 编写 Javascript 代码。第一个图表对象 chartObject1 显示正确，但第二个图表 chartObject2 不显示标题，因为我试图在文字定义之外设置标题文本属性。

为什么它不让我使用 chartObject2.title.text = "chart2"; 设置属性？

<?php
$chart_text = <<<EOD
<script type="text/javascript">
var chartObject1 = Object;
$(document).ready(function(){
    chartObject1 = new Highcharts.Chart({
        chart: {
            renderTo: 'chart1',
            type: 'bar'
        },
        title: {
            text: 'chart1'
            },
        xAxis: {
            categories: ['Apples', 'Bananas', 'Oranges']
        },
        yAxis: {
            title: {
                text: 'Fruit eaten'
            }
        },
        series: [{
            name: 'Jane',
            data: [1, 0, 4]},
            {
            name: 'John',
            data: [5, 7, 3]}]
        });
});
</script>
EOD;
print ($chart_text);
$chart_text = <<<EOD
<script type="text/javascript">
var chartObject2 = Object;
$(document).ready(function(){
chartObject2 = new Highcharts.Chart({
        chart: {
            renderTo: 'chart2',
            type: 'bar'
        },
        xAxis: {
            categories: ['Spiders', 'Grasshoppers', 'Scorpions']
        },
        yAxis: {
            title: {
                text: 'Bugs eaten'
            }
        },
        series: [{
            name: 'Jane',
            data: [1, 0, 4]},
        {
            name: 'John',
            data: [5, 7, 3]}]
    });
    chartObject2.title.text = "chart2";
    });
</script>
EOD;
print ($chart_text);
?>