> 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/compare-files/semantic.md).
# Compare PDF Changes in Semantic Text Using JavaScript
Effortlessly compare semantic text elements like headers and paragraphs, generate difference summaries, and add highlights for easy review. Compare and annotate documents side by side with ease. Creat
{% hint style="info" %}
**Requirements**
*These packages are required to use these features in production. Trial keys have unlimited access to all features*
Package: CompareLive demo
{% endhint %}
Compare changes in semantic categories, such as headers, paragraphs, numbers, and generate a document with a summary of differences for easy review.
## Highlighting differences
Using this method you can compare documents and add highlight annotations to mark the differences in side-by-side view.
{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}
```js
WebViewer({
fullAPI: true,
disableMultiViewerComparison: true, // Disable default compare buttons
}, document.getElementById('viewer'))
.then((instance) => {
const { UI, Core } = instance;
const { Annotations } = Core;
const { Color } = Annotations;
instance.UI.openElements(['comparePanel']);
UI.addEventListener(UI.Events.MULTI_VIEWER_READY, () => {
const [documentViewer1, documentViewer2] = Core.getDocumentViewers();
const startCompare = async () => {
const shouldCompare = documentViewer1.getDocument() && documentViewer2.getDocument();
if (shouldCompare) { // Check if both documents loaded before comparing
const beforeColor = new Color(21, 205, 131, 0.4);
const afterColor = new Color(255, 73, 73, 0.4);
const options = { beforeColor, afterColor };
const { doc1Annotations, doc2Annotations, diffCount } = await documentViewer1.startSemanticDiff(documentViewer2, options);
}
}
documentViewer1.addEventListener('documentLoaded', startCompare);
documentViewer2.addEventListener('documentLoaded', startCompare);
documentViewer1.loadDocument('https://www.pdftron.com/compare1.pdf');
documentViewer2.loadDocument('https://www.pdftron.com/compare2.pdf');
});
UI.enableFeatures([UI.Feature.MultiViewerMode]);
});
```
{% endcode %}
{% endtab %}
{% endtabs %}
## Creating a new document with differences
Using this method you can create a new document that has alternating pages from both input documents with highlighted differences
{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}
```js
const wvElement = document.getElementById('viewer');
WebViewer({
fullAPI: true,
}, document.getElementById('viewer'))
.then(async instance => {
const { documentViewer, PDFNet } = instance.Core;
await PDFNet.initialize();
const newDoc = await PDFNet.PDFDoc.create();
await newDoc.lock();
const doc1 = await PDFNet.PDFDoc.createFromURL('./files/semantic_test_doc_1.pdf');
const doc2 = await PDFNet.PDFDoc.createFromURL('./files/semantic_test_doc_2.pdf');
await newDoc.appendTextDiffDoc(doc1, doc2);
await newDoc.unlock();
instance.UI.loadDocument(newDoc);
// wait until the document has been loaded
documentViewer.addEventListener('documentLoaded', () => {
instance.UI.setLayoutMode(instance.UI.LayoutMode.FacingContinuous);
});
});
```
{% endcode %}
{% endtab %}
{% endtabs %}
[TextDiffOptions](https://sdk.apryse.com/api/web/Core.PDFNet.PDFDoc.TextDiffOptions.html)
See our [semantic text compare interactive demo](https://showcase.apryse.com/semantic-text-compare) to try it out now, or start coding now with the [semantic compare sample](/web/get-started/samples/diff.md).
---
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