Open Presentations in Node.js via .NET

Overview

Aspose.Slides for Node.js via .NET opens PowerPoint and OpenDocument presentations, such as PPTX, PPT, and ODP files, from a file path or from a Node.js Buffer. This article shows both ways, reads the number of slides, and saves an opened presentation in another format.

The examples expect a presentation named sample.pptx in the project folder that you set up in Installation. Any PowerPoint presentation will do. Save each example as a .js file in the project folder and run it from that folder with node.

Open a Presentation from a File

To open a presentation, pass its path to the Presentation constructor. Aspose.Slides detects the format from the file content rather than from the extension, so the same code opens PPTX, PPT, and ODP files. A relative path is resolved against the current working directory, which is the project folder when you run the script from there.

const { Presentation } = require("aspose.slides.via.net");

const presentation = new Presentation("sample.pptx");
try {
    console.log("Slide count: " + presentation.slides.count);
} finally {
    presentation.dispose();
}

The script prints the number of slides in sample.pptx, for example Slide count: 9. The count property of the slides collection includes hidden slides. Call dispose in a finally block, as shown, so that the .NET resources behind the presentation are released even if your code fails.

Open a Presentation from a Buffer

When a presentation comes from a database, an HTTP upload, or another source that gives you bytes rather than a file path, pass a Node.js Buffer as the second constructor argument and null as the first. The following example reads sample.pptx into a buffer to stand in for such a source:

const fs = require("fs");
const { Presentation } = require("aspose.slides.via.net");

const presentationData = fs.readFileSync("sample.pptx");

const presentation = new Presentation(null, presentationData);
try {
    console.log("Slide count: " + presentation.slides.count);
} finally {
    presentation.dispose();
}

The script prints the same slide count as the previous example. The second argument must be a Buffer. For any other type, such as a Uint8Array, the constructor does not report an error; it creates a new presentation with one empty slide instead. Convert other binary types with Buffer.from first.

Save a Presentation in Another Format

To convert a presentation to another presentation format, open it and save it with a different SaveFormat value. The following example prints the format that Aspose.Slides detected, which the sourceFormat property returns, and saves the presentation as an OpenDocument presentation:

const { Presentation, SaveFormat } = require("aspose.slides.via.net");

const presentation = new Presentation("sample.pptx");
try {
    console.log("Source format: " + presentation.sourceFormat);
    presentation.save("sample.odp", SaveFormat.Odp);
} finally {
    presentation.dispose();
}

The script prints Source format: Pptx and writes sample.odp, which contains the same slides. sourceFormat returns Ppt, Pptx, or Odp. To save as PDF or as images instead, see Convert PowerPoint to PDF and Convert Slides to Images.

FAQ

How do I open a password-protected presentation?

Create a LoadOptions object, set its password property, and pass the object as the third constructor argument: new Presentation("protected.pptx", null, loadOptions). Without the correct password, the constructor throws an error.

Why does the constructor throw an Error with an empty message?

When the Presentation constructor fails in .NET, for example because the file is missing, is not a presentation, or needs a different password, JavaScript receives an Error whose message is empty. Before you open a file, check that it exists relative to the working directory, for example with fs.existsSync.

Which formats can I open?

PowerPoint and OpenDocument presentation formats, including PPT, PPTX, PPS, POT, POTX, PPTM, ODP, OTP, and FODP.

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