用JavaScript通过C++管理日期轴
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可能的使用场景
当你用日期数据创建图表，并且日期沿水平（类别）轴绘制时，Aspose.Cells for JavaScript通过C++会自动将类别轴更改为日期（时间尺度）轴。 日期轴以特定间隔或基本单位（例如天数、月份或年份）按年代顺序显示日期，即使工作表上的日期不是按顺序或基本单位相同。 默认情况下，Aspose.Cells根据工作表数据中两个日期之间的最小差异确定日期轴的基本单位。例如，如果你的数据为股票价格，两个日期间的最小差异为七天，Excel会将基本单位设为天，但你可以将基本单位改为月或年，以观察股票在较长时间段内的表现。
处理日期轴就像处理Microsoft Excel一样
请参阅以下示例代码，此代码创建一个新的Excel文件并将图表的值放在第一个工作表中。 然后，我们添加一个图表并设置Axis的类型 到Axis.categoryType，然后将基本单位设置为天数。
示例代码
<!DOCTYPE html>
<html>
<head>
<title>Aspose.Cells Date Axis Chart Example</title>
</head>
<body>
<h1>Date Axis Chart Example</h1>
<input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
<button id="runExample">Run Example</button>
<a id="downloadLink" style="display: none;">Download Result</a>
<div id="result"></div>
</body>
<script src="aspose.cells.js.min.js"></script>
<script type="text/javascript">
const { Workbook, SaveFormat, ChartType, CategoryType, TimeUnit, ChartTextDirectionType, FillType } = AsposeCells;
AsposeCells.onReady({
license: "/lic/aspose.cells.enc",
fontPath: "/fonts/",
fontList: [
"arial.ttf",
"NotoSansSC-Regular.ttf"
]
}).then(() => {
console.log("Aspose.Cells initialized");
});
document.getElementById('runExample').addEventListener('click', async () => {
const fileInput = document.getElementById('fileInput');
if (!fileInput.files.length) {
document.getElementById('result').innerHTML = '<p style="color: red;">Please select an Excel file.</p>';
return;
}
const file = fileInput.files[0];
const arrayBuffer = await file.arrayBuffer();
// Instantiating a Workbook object from uploaded file
const workbook = new Workbook(new Uint8Array(arrayBuffer));
// Get the first worksheet
const worksheet = workbook.worksheets.get(0);
// Shortcut to cells collection
const cells = worksheet.cells;
// Add the sample values to cells
cells.get("A1").value = "Date";
// 14 means datetime format
const style = cells.style;
style.number = 14;
// Put values to cells for creating chart
const cellA2 = cells.get("A2");
cellA2.style = style;
cellA2.value = new Date(Date.UTC(2022, 5, 26));
const cellA3 = cells.get("A3");
cellA3.style = style;
cellA3.value = new Date(Date.UTC(2022, 4, 22));
const cellA4 = cells.get("A4");
cellA4.style = style;
cellA4.value = new Date(Date.UTC(2022, 7, 3));
cells.get("B1").value = "Price";
cells.get("B2").value = 40;
cells.get("B3").value = 50;
cells.get("B4").value = 60;
// Add a chart to the worksheet
const chartIndex = worksheet.charts.add(ChartType.Column, 9, 6, 21, 13);
// Access the instance of the newly added chart
const chart = worksheet.charts.get(chartIndex);
// Add SeriesCollection (chart data source) to the chart ranging from "A1" cell to "B4"
// Converted setter to property assignment (range and boolean passed as array)
chart.chartDataRange = ["A1:B4", true];
// Set the Axis type to Date time
chart.categoryAxis.categoryType = CategoryType.TimeScale;
// Set the base unit for CategoryAxis to days
chart.categoryAxis.baseUnitScale = TimeUnit.Days;
// Set the direction for the axis text to be vertical
chart.categoryAxis.tickLabels.directionType = ChartTextDirectionType.Vertical;
// Fill the PlotArea area with nothing
chart.plotArea.area.fillFormat.fillType = FillType.None;
// Set max value of Y axis.
chart.valueAxis.maxValue = 70;
// Set major unit.
chart.valueAxis.majorUnit = 10;
// Saving the modified Excel file and provide download link
const outputData = workbook.save(SaveFormat.Xlsx);
const blob = new Blob([outputData]);
const downloadLink = document.getElementById('downloadLink');
downloadLink.href = URL.createObjectURL(blob);
downloadLink.download = 'DateAxis.xlsx';
downloadLink.style.display = 'block';
downloadLink.textContent = 'Download Excel File';
document.getElementById('result').innerHTML = '<p style="color: green;">Chart created successfully! Click the download link to get the modified file.</p>';
});
</script>
</html>