> 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/samples/viewerdigitalsignaturevalidationtest.md).

# Validate Digital Signature - Sample Code

View digital signature validation information in PDFs using JavaScript. Makes it easy to see the whether a signature is valid when viewing a PDF.

{% hint style="info" %}
**Requirements**

*These packages are required to use these features in production. Trial keys have unlimited access to all features*

<a href="/web/get-started/readme.md" class="button primary">Web SDK</a><a href="https://apryse.com/capabilities#DigitalSignature" class="button primary">Package: Digital Signature</a><a href="/web/full-api/full-api-overview.md" class="button primary">Full API</a><a href="https://showcase.apryse.com/digital-signatures" class="button primary">Live demo</a>
{% endhint %}

This JavaScript sample illustrates how to view digital signature validation information in a PDF document.

### **Implementation steps**

To validate a digital signature with WebViewer:

Step 1: Follow [get started in your preferred web stack for WebViewer](/web/get-started/readme.md) Step 2: [Enable the full API ](/web/full-api/full-api-overview.md)by passing the `fullAPI` option into the WebViewer constructor Step 3: Add the sample code provided in this guide

This full sample is included in the [manual download of WebViewer.](/web/get-started/manually.md#1-download-webviewer)

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

```js
(() => {
  const parentDocument = window.parent.document;
  const certSelect = parentDocument.getElementById('certificate-select');
  const certUrlForm = parentDocument.getElementById('certificate-url-form');
  const docSelect = parentDocument.getElementById('document-select');
  const docUrlForm = parentDocument.getElementById('document-url-form');
  const filePicker = parentDocument.getElementById('file-picker');
  const certUrl = parentDocument.getElementById('certificate-url');
  const docUrl = parentDocument.getElementById('document-url');

  window.addEventListener('viewerLoaded', () => {
    const instance = window.instance;
    const { VerificationOptions, openElements, loadDocument } = instance.UI;
    const { documentViewer } = instance.Core;

    const initialCert = 'https://pdftron.s3.amazonaws.com/downloads/pl/waiver.cer';
    VerificationOptions.addTrustedCertificates([initialCert]);

    documentViewer.addEventListener(
      'documentLoaded',
      () => {
        openElements(['signaturePanel']);
      },
      { once: true }
    );

    certSelect.addEventListener('change', e => {
      VerificationOptions.addTrustedCertificates([e.target.value]);
    });

    certUrlForm.addEventListener('submit', e => {
      e.preventDefault();
      certSelect.value = '';
      VerificationOptions.addTrustedCertificates([certUrl.value]);
    });

    docSelect.addEventListener('change', e => {
      loadDocument(e.target.value);
    });

    docUrlForm.addEventListener('submit', e => {
      e.preventDefault();
      docSelect.value = '';
      loadDocument(docUrl.value);
    });

    filePicker.addEventListener('change', e => {
      const file = e.target.files[0];

      if (!file) {
        return;
      }

      const ext = file.name.slice(file.name.lastIndexOf('.') + 1);

      if (ext === 'cer') {
        certSelect.value = '';
        VerificationOptions.addTrustedCertificates([file]);
      } else if (ext === 'pdf') {
        docSelect.value = '';
        loadDocument(file);
      }
    });
  });
})();
// eslint-disable-next-line spaced-comment
//# sourceURL=config.js
```

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


---

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