> For the complete documentation index, see [llms.txt](https://docs.apryse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.apryse.com/web/get-started/guides/features/basics/open.md).

# Open a PDF using JavaScript

Learn how to open a PDF document from a memory buffer with full source code examples. Explore the PDFDoc constructor and best practices for handling PDF documents efficiently. The Apryse Web SDK strea

{% hint style="warning" %}
Make sure you have [Full API enabled in WebViewer.](/web/what-is-webviewer/full-api.md)
{% endhint %}

To open a PDF document.

{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}

```js
// open document from the filesystem or URL
async function main() {
  const doc = await PDFNet.PDFDoc.createFromURL(filename);

  // optionally read a PDF document from a stream
  const file = await PDFNet.Filter.createURLFilter(filename);
  const doc_stream = await PDFNet.PDFDoc.createFromFilter(file);

  // or pass-in a memory buffer
  const file_sz = await file.size();
  const file_reader = await PDFNet.FilterReader.create(file);
  const mem = await file_reader.read(file_sz);
  const doc_mem = await PDFNet.PDFDoc.createFromBuffer(mem);
}
PDFNet.runWithCleanup(main);
```

{% endcode %}
{% endtab %}
{% endtabs %}

[Read & write a PDF file from/to memory buffer](/web/get-started/samples.md#pdfdocmemory) Full source code which illustrates how to read/write a PDF document from/to memory buffer. This is useful for applications that work with dynamic PDF documents that don't need to be saved/read from a disk.

## About opening a document

The PDFDoc constructor creates a PDF document from scratch:

{% hint style="warning" %}
**PDFDoc.Close()**

When you are finished with a PDFDoc object, the PDFDoc.Close() method should be called to clean up memory, file handles, and resources.
{% endhint %}

{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}

```js
async function main() {
  const doc = await PDFNet.PDFDoc.create();
}
PDFNet.runWithCleanup(main);
```

{% endcode %}
{% endtab %}
{% endtabs %}

A newly-created document does not yet contain any pages. See the [accessing pages](/web/get-started/guides/features/basics/pages.md) section for details on creating new pages and working with existing pages.

Using Apryse SDK, you can open a document from a serialized file, from a memory buffer, or from a Filter stream.

To open an existing PDF document from a file, specify its file path in the PDFDoc constructor:

{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}

```js
async function main() {
  const doc = await PDFNet.PDFDoc.createFromURL(filename);
}
PDFNet.runWithCleanup(main);
```

{% endcode %}
{% endtab %}
{% endtabs %}

Here's how to open an existing PDF document from a memory buffer:

{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}

```js
async function main() {
  const file = await PDFNet.Filter.createURLFilter(filename);
  const file_sz = await file.size();
  const file_reader = await PDFNet.FilterReader.create(file);
  const mem = await file_reader.read(file_sz);
  const doc_mem = await PDFNet.PDFDoc.createFromBuffer(mem);
}
PDFNet.runWithCleanup(main);
```

{% endcode %}
{% endtab %}
{% endtabs %}

It's also easy to open a PDF document from a [MemoryFilter or a custom Filter ](/web/low-level-pdf-api/filters.md).

After creating a PDFDoc object, it's good practice to call `InitSecurityHandler()` on it. If the document is encrypted, calling the method will decrypt it. If the document is not encrypted, calling the method is harmless.

{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}

```js
async function main() {
  const doc = await PDFNet.PDFDoc.createFromURL(filename);
  if (!doc.initSecurityHandler()) {
    console.log("Document authentication error...");
    return;
  }
}
PDFNet.runWithCleanup(main);
```

{% endcode %}
{% endtab %}
{% endtabs %}


---

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