Different Ways to Open Files with JavaScript via C++

With Aspose.Cells, it is simple to open files, for example, to retrieve data, or to use a designer template to speed up the development process.

How to Open an Excel File via a Path

Developers can open a Microsoft Excel file using its file path on the local computer by specifying it in the Workbook class constructor. Simply pass the path in the constructor as a string. Aspose.Cells will automatically detect the file format type.

<!DOCTYPE html>
<html>
    <head>
        <title>Aspose.Cells Example - Open Workbook</title>
    </head>
    <body>
        <h1>Open Workbook Example</h1>
        <input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
        <button id="runExample">Open Workbook</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, Utils } = 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 by opening the uploaded Excel file
            const workbook1 = new Workbook(new Uint8Array(arrayBuffer));
            console.log("Workbook opened using file successfully!");

            // Display basic info about the opened workbook
            document.getElementById('result').innerHTML = `<p style="color: green;">Workbook opened successfully! Worksheets count: ${workbook1.worksheets.count}</p>`;
        });
    </script>
</html>

How to Open an Excel File via a Stream

It is also simple to open an Excel file as a stream. To do so, use an overloaded version of the constructor that takes the Stream object that contains the file.

<!DOCTYPE html>
<html>
    <head>
        <title>Aspose.Cells Example - Stream to Workbook</title>
    </head>
    <body>
        <h1>Open Excel Stream Example (Browser)</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, Utils } = 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');
            const resultDiv = document.getElementById('result');

            if (!fileInput.files.length) {
                resultDiv.innerHTML = '<p style="color: red;">Please select an Excel file.</p>';
                return;
            }

            // Read the selected file as an ArrayBuffer (equivalent to reading a stream in JavaScript)
            const file = fileInput.files[0];
            const arrayBuffer = await file.arrayBuffer();

            // Instantiate a Workbook object from the file content
            const workbook = new Workbook(new Uint8Array(arrayBuffer));

            // Access the first worksheet in the Excel file
            const worksheet = workbook.worksheets.get(0);

            // Example modification: set A1 to indicate file was loaded (demonstrates cell value setter conversion)
            const cell = worksheet.cells.get(0, 0);
            cell.value = "Loaded from stream";

            // Save the modified workbook as Excel97-2003 (.xls) since original was .xls in JavaScript example
            const outputData = workbook.save(SaveFormat.Excel97To2003);
            const blob = new Blob([outputData]);
            const downloadLink = document.getElementById('downloadLink');
            downloadLink.href = URL.createObjectURL(blob);
            downloadLink.download = 'output.out.xls';
            downloadLink.style.display = 'block';
            downloadLink.textContent = 'Download Modified Excel File';

            resultDiv.innerHTML = '<p style="color: green;">Workbook processed successfully! Click the download link to get the modified file.</p>';
        });
    </script>
</html>

How to Open a File with Data only

To open a file with data only, use the LoadOptions and LoadFilter classes to set the related attributes and options of the classes for the template file to be loaded.

<!DOCTYPE html>
<html>
    <head>
        <title>Aspose.Cells LoadOptions Example</title>
    </head>
    <body>
        <h1>LoadOptions with LoadFilter Example</h1>
        <input type="file" id="fileInput" accept=".xlsx" />
        <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, LoadOptions, LoadFormat, LoadFilter, LoadDataFilterOptions, SaveFormat, Utils } = 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 .xlsx file.</p>';
                return;
            }

            const file = fileInput.files[0];
            const arrayBuffer = await file.arrayBuffer();

            // Instantiate LoadOptions specified by the LoadFormat
            const loadOptions = new LoadOptions(LoadFormat.Xlsx);

            // Set LoadFilter property to load only data & cell formatting
            loadOptions.loadFilter = new LoadFilter(LoadDataFilterOptions.CellData);

            // Create a Workbook object and opening the file from the uploaded file stream
            const workbook = new Workbook(new Uint8Array(arrayBuffer), loadOptions);

            // Indicate success
            document.getElementById('result').innerHTML = '<p style="color: green;">File data imported successfully!</p>';

            // Prepare download of the loaded workbook (optional)
            const outputData = workbook.save(SaveFormat.Xlsx);
            const blob = new Blob([outputData]);
            const downloadLink = document.getElementById('downloadLink');
            downloadLink.href = URL.createObjectURL(blob);
            downloadLink.download = 'output.xlsx';
            downloadLink.style.display = 'block';
            downloadLink.textContent = 'Download Excel File';
        });
    </script>
</html>

How to Load Visible Sheets only

While loading a Workbook, sometimes you may only need data in visible worksheets in a workbook. Aspose.Cells allows you to skip data in invisible worksheets while loading a workbook. To do this, create a custom function that inherits the LoadFilter class and pass its instance to LoadOptions.loadFilter property.

<!DOCTYPE html>
<html>
    <head>
        <title>Aspose.Cells Example</title>
    </head>
    <body>
        <h1>Aspose.Cells Example</h1>
        <input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
        <button id="runExample">Run Example (Create if no file selected)</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, LoadOptions, LoadFilter, Utils } = 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');
            let bytes;
            let createdOutputData;

            if (fileInput.files.length) {
                // Load from user-selected file
                const arrayBuffer = await fileInput.files[0].arrayBuffer();
                bytes = new Uint8Array(arrayBuffer);
            } else {
                // Create a sample workbook in memory
                const createWorkbook = new Workbook();

                // Put some data in first cell of all 3 sheets
                createWorkbook.worksheets.get("Sheet1").cells.get("A1").value = "Aspose";
                createWorkbook.worksheets.add("Sheet2").cells.get("A1").value = "Aspose";
                createWorkbook.worksheets.add("Sheet3").cells.get("A1").value = "Aspose";
                createWorkbook.worksheets.get("Sheet3").isVisible = false;

                // Save the created workbook to bytes
                createdOutputData = createWorkbook.save(SaveFormat.Xlsx);
                bytes = createdOutputData instanceof Uint8Array ? createdOutputData : new Uint8Array(createdOutputData);

                // Provide download link for the created workbook
                const blob = new Blob([bytes]);
                const downloadLink = document.getElementById('downloadLink');
                downloadLink.href = URL.createObjectURL(blob);
                downloadLink.download = 'output.xlsx';
                downloadLink.style.display = 'block';
                downloadLink.textContent = 'Download Created Excel File';
            }

            // Prepare load options and load filter
            const loadOptions = new LoadOptions();
            loadOptions.loadFilter = new LoadFilter();

            // Load the workbook using the bytes and load options
            const loadWorkbook = new Workbook(bytes, loadOptions);

            // Read values from A1 of Sheet1, Sheet2, Sheet3
            const sheet1A1 = loadWorkbook.worksheets.get("Sheet1").cells.get("A1").value;
            const sheet2A1 = loadWorkbook.worksheets.get("Sheet2").cells.get("A1").value;
            const sheet3A1 = loadWorkbook.worksheets.get("Sheet3").cells.get("A1").value;

            // Log to console and show in the page
            console.log(`Sheet1: A1: ${sheet1A1}`);
            console.log(`Sheet2: A1: ${sheet2A1}`);
            console.log(`Sheet3: A1: ${sheet3A1}`);

            document.getElementById('result').innerHTML =
                `<p>Sheet1: A1: ${sheet1A1}</p>
                 <p>Sheet2: A1: ${sheet2A1}</p>
                 <p>Sheet3: A1: ${sheet3A1}</p>
                 <p style="color: green;">Operation completed successfully!</p>`;
        });
    </script>
</html>

<!DOCTYPE html>
<html>
    <head>
        <title>Aspose.Cells Example</title>
        <meta charset="utf-8" />
    </head>
    <body>
        <h1>CustomLoad Example</h1>
        <p>Select an Excel file to evaluate sheets with CustomLoad.startSheet()</p>
        <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, LoadDataFilterOptions } = AsposeCells;
        
        AsposeCells.onReady({
            license: "/lic/aspose.cells.enc",
            fontPath: "/fonts/",
            fontList: [
                "arial.ttf",
                "NotoSansSC-Regular.ttf"
            ]
        }).then(() => {
            console.log("Aspose.Cells initialized");
        });

        class CustomLoad {
            startSheet(sheet) {
                if (sheet.isVisible()) {
                    // Load everything from visible worksheet
                    this.loadDataFilterOptions = LoadDataFilterOptions.All;
                } else {
                    // Load nothing
                    this.loadDataFilterOptions = LoadDataFilterOptions.Structure;
                }
            }
        }

        document.getElementById('runExample').addEventListener('click', async () => {
            const fileInput = document.getElementById('fileInput');
            const resultDiv = document.getElementById('result');

            if (!fileInput.files.length) {
                resultDiv.innerHTML = '<p style="color: red;">Please select an Excel file.</p>';
                return;
            }

            const file = fileInput.files[0];
            const arrayBuffer = await file.arrayBuffer();

            // Instantiate workbook from uploaded file
            const workbook = new Workbook(new Uint8Array(arrayBuffer));

            const custom = new CustomLoad();

            let html = '<h2>CustomLoad Results</h2>';
            html += '<ul>';

            for (let i = 0; i < workbook.worksheets.count; i++) {
                const sheet = workbook.worksheets.get(i);
                custom.startSheet(sheet);
                html += `<li><strong>${sheet.name}</strong>: loadDataFilterOptions = ${custom.loadDataFilterOptions}</li>`;
            }

            html += '</ul>';
            resultDiv.innerHTML = html;
        });
    </script>
</html>

An exception will be thrown if you try to open non-native Excel files or other file formats (for example PPT/PPTX, DOC/DOCX, etc.) using Aspose.Cells.

There are fair chances that the Workbook constructor may throw OutOfMemoryError while loading large spreadsheets. This exception suggests that the available memory is insufficient to completely load the spreadsheet into memory; therefore, the spreadsheet has to be loaded while enabling the Memory Preferences.

Open Different Microsoft Excel Versions Files with JavaScript via C++