> 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/showcase-demo-accessible-reading-order.md).

# Accessible Reading Order Showcase Demo Code Sample

Easily load accessible PDF and PDF/UA documents and interact with them via screen reader directly in your browse, without server-side dependencies.

{% 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://showcase.apryse.com/accessible-reading-order" class="button primary">Live demo</a>
{% endhint %}

Easily load accessible PDF and PDF/UA documents and interact with them via screen reader directly in your browser, without server-side dependencies.

This demo allows you to:

* Load your accessible PDF or PDF/UA documents
* Interact with document via the document reader
* Advance to the next segment or return to a previous segment

**Implementation steps** To add accessibility via a screen reader to a PDF or PDF/UA with WebViewer:

Step 1: Choose your [preferred web stack](/web/get-started/readme.md) Step 2: Add the ES6 JavaScript sample code provided in this guide

Once you generate your license key, it will automatically be included in your sample code below.

{% @apryse-license-key/apryse-license-key platform="WEB\_VIEWER" variant="compact" %}

<pre class="language-js" data-line-numbers><code class="lang-js">/* ES6 Compliant Syntax */
/* GitHub Copilot v1.0, Claude 3.5 Sonnet, August 24, 2025 */
/* File: index.js */

import WebViewer from '@pdftron/webviewer';

// Accessible Reading Order section
//
// Code to load accessible PDFs and PDF/UA documents and interact with them
// via screen reader directly in your browser, without server-side
// dependencies
//

const defaultDoc = 'https://apryse.s3.us-west-1.amazonaws.com/public/files/samples/PDFUA_AcademicAbstract.pdf';

let isInAccessibleReadingOrderMode = false;
let isAccessibleReadingOrderModeNoStructure = false;
let currentPage = 1;
let prevItem = null;
let currentText = '';
let isMuted = false;

// Reset all variables when a new document is loaded
const onDocumentLoaded = async () => {
    // Reset the demo variables
    isInAccessibleReadingOrderMode = false;
    isAccessibleReadingOrderModeNoStructure = false;
    currentPage = 1;
    prevItem = null;
    currentText = '';
};

// Set accessible reading order mode no structure state
const onAccessibleReadingOrderModeNoStructure = () => {
    isAccessibleReadingOrderModeNoStructure = true;
    console.log('No structure detected in the document.');

    // Update UI controls
    updateUIControls();
};

const onAccessibleReadingOrderModeStarted = () => {
    isInAccessibleReadingOrderMode = true;
    console.log('Accessible reading order mode started.');

    // Update UI controls
    updateUIControls();
};

const onAccessibleReadingOrderModeEnded = () => {
    isInAccessibleReadingOrderMode = false;
    console.log('Accessible reading order mode ended.');

    // Update UI controls
    updateUIControls();
};

const customizeUI = async (instance) => {
    const { documentViewer } = instance.Core;

    // Set the default document to load
    await instance.Core.documentViewer.loadDocument(defaultDoc, {
        extension: 'pdf',
    });

    // Initialize the accessible reading order mode
    const manager = documentViewer.getAccessibleReadingOrderManager();
    await manager.startAccessibleReadingOrderMode();
    isInAccessibleReadingOrderMode = manager.isInAccessibleReadingOrderMode();

    // Add event listeners
    documentViewer.addEventListener('documentLoaded', onDocumentLoaded);
    manager.addEventListener('accessibleReadingOrderModeNoStructure', onAccessibleReadingOrderModeNoStructure);
    manager.addEventListener('accessibleReadingOrderModeStarted', onAccessibleReadingOrderModeStarted);
    manager.addEventListener('accessibleReadingOrderModeEnded', onAccessibleReadingOrderModeEnded);
};

const getFirstElementOnPage = (instance, page) => {
    const allContentElements = Array.from(
        instance.Core.documentViewer.getViewerElement()
            .querySelectorAll(`[data-element^="a11y-reader-content-${page}_"]`)
    );
    return allContentElements.length > 0 ? allContentElements[0] : null;
};

const getAllContentElements = (instance, page) => {
    return Array.from(
        instance.Core.documentViewer.getViewerElement()
            .querySelectorAll(`[data-element^="a11y-reader-content-${page}_"]`)
    );
};

// Toggle mute
const toggleMute = () => {
    const speechSynth = window?.speechSynthesis;
    if (isMuted) {
        speechSynth?.resume();
    } else {
        speechSynth?.pause();
    }
    isMuted = !isMuted;
};

// Highlight the current text element
const highlightCurrentElementAndChangePage = (instance, element) => {
    if (!element) return;
    element.style.border = '2px solid rgba(0, 0, 0, 0.6)';
    element.style.borderRadius = '4px';
    element.style.boxSizing = 'border-box';

    const dataElement = element.getAttribute('data-element') || '';
    let elementPage = -1;

    if (dataElement &#x26;&#x26; dataElement.startsWith('a11y-reader-content-')) {
        // Parse the page number from a11y-reader-content-{page}-{block}
        const parts = dataElement.split('-');
        if (parts.length > 4) {
            // Should have at least 4 parts to extract the page number       
            elementPage = parseInt(parts[3], 10);
        }
    }

    if (elementPage > 0) {
        const currPage = instance?.Core.documentViewer.getCurrentPage();

        if (elementPage !== currPage) {
            instance?.Core.documentViewer.setCurrentPage(elementPage);
        }
    }
};

// Process selected content
const processSelectedContent = (instance, content) => {
    if (!content) return;

    highlightCurrentElementAndChangePage(instance, content);
    const typeDescription = getElementTypeDescription(content);
    prevItem = content;

    const baseText = content.textContent || '';
    const text = typeDescription + baseText;
    currentText = text;

    speechSynthesis.cancel(); // Cancel any ongoing speech synthesis
    readText(text, isMuted);
};

// Clear highlight from the previous element
const clearPreviousHighlight = () => {
    if (prevItem) {
        prevItem.style.border = 'none';
    }
};

// Get the next element in the reading order
const nextElement = (instance) => {
    const currPage = currentPage;

    clearPreviousHighlight();

    let content = null;

    if (prevItem) {
        // Find siblings that have the a11y-reader-content prefix
        const allContentElements = getAllContentElements(instance, currPage);
        const currentIndex = allContentElements.findIndex((el) => el === prevItem);

        // Get the next element if available
        if (currentIndex !== -1 &#x26;&#x26; currentIndex &#x3C; allContentElements.length - 1) {
            content = allContentElements[currentIndex + 1];
        }
    } else {
        content = getFirstElementOnPage(instance, currPage);
    }


    if (!content) {
        content = getFirstElementOnPage(instance, currPage + 1);

        if (content) {
            currentPage += 1;
        } else {
            // Reset to start if no more content
            currentPage = 1;
            content = getFirstElementOnPage(instance, 1);
        }
    }

    if (content) {
        processSelectedContent(instance, content);
    }
};

// Get the previous element in the reading order
const previousElement = (instance) => {
    const currPage = currentPage;

    clearPreviousHighlight();
    let content = null;

    if (prevItem) {
        // Find siblings that have the a11y-reader-content prefix
        const allContentElements = getAllContentElements(instance, currPage);
        const currentIndex = allContentElements.findIndex((el) => el === prevItem);

        // Get the previous element if available
        if (currentIndex > 0) {
            content = allContentElements[currentIndex - 1];
        } else if (currPage > 1) {
            // if we are at the first element of the page, try to get the last element of the previous page
            const prevPageElements = getAllContentElements(instance, currPage - 1);

            if (prevPageElements.length > 0) {
                content = getFirstElementOnPage(instance, currPage - 1);
                currentPage -= 1;
            }
        }
    } else {
        // No current item yet, get the first one
        content = getFirstElementOnPage(instance, currPage);
    }

    // If no content found, reset to the first element of the first page
    if (!content) {
        currentPage = 1;
        content = getFirstElementOnPage(instance, 1);
    }

    if (content) {
        processSelectedContent(instance, content);
    }
};

// Speech Synthesis section
// 
// Code to read the text content of the document using the browser's
// speech synthesis API
//

const voiceIndex = 0;
const pitch = 1;
const rate = 1;
const volume = 1;

const readText = (documentText, isMuted) => {
    const speechSynth = window?.speechSynthesis;
    const utterance = new window.SpeechSynthesisUtterance(documentText);
    if (voiceIndex) {
        utterance.voice = speechSynth?.getVoices()[voiceIndex];
    }
    utterance.pitch = pitch;
    utterance.rate = rate;
    utterance.volume = isMuted ? 0 : volume;

    if (speechSynth?.speaking) {
        speechSynth?.resume();
    } else {
        speechSynth?.speak(utterance);
    }
};

const getElementTypeDescription = (element) => {
    const role = element.getAttribute('role')?.toLowerCase() || '';

    if (role === 'heading') {
        const level = element.getAttribute('aria-level');
        if (level) {
            return `Heading level ${level}, `;
        }
    }

    // Check for common semantic elements based on tag name or class
    const tagName = element.tagName?.toLowerCase() || '';
    if (tagName) {
        if (tagName === 'h1') return 'Heading level 1, ';
        if (tagName === 'h2') return 'Heading level 2, ';
        if (tagName === 'h3') return 'Heading level 3, ';
        if (tagName === 'h4') return 'Heading level 4, ';
        if (tagName === 'h5') return 'Heading level 5, ';
        if (tagName === 'h6') return 'Heading level 6, ';

        if (tagName === 'img' || role === 'img') {
            const alt = element.getAttribute('alt');
            if (alt) return `Image, ${alt}, `;
            return 'Image, ';
        }

        if (tagName === 'figure') return 'Figure, ';
        if (tagName === 'table' || role === 'table') return 'Table, ';
        if (tagName === 'ul' || role === 'list') return 'List, ';
        if (tagName === 'ol') return 'Ordered list, ';
        if (tagName === 'li' || role === 'listitem') return 'List item, ';
        if (tagName === 'a' || role === 'link') return 'Link, ';
        if (tagName === 'button' || role === 'button') return 'Button, ';
        if (tagName === 'input' || role === 'textbox') return 'Input field, ';
    }

    return '';
};


// WebViewer section
// 
// This code initializes the WebViewer with the basic settings
// that are found in the default showcase WebViewer
//

const searchParams = new URLSearchParams(window.location.search);
const history = window.history || window.parent.history || window.top.history;
const licenseKey = '<code class="expression">visitor.claims.wvKey || "YOUR_WEBVIEWER_LICENSE_KEY"</code>';
const element = document.getElementById('viewer');

// Initialize WebViewer with the specified settings
WebViewer({
    path: '/lib',
    fullAPI: true, // Required for Accessible Reading Order
    licenseKey: licenseKey,
    enableFilePicker: true,
}, element).then((instance) => {
    // Enable the measurement toolbar so it appears with all the other tools, and disable Cloudy rectangular tool
    const cloudyTools = [
        instance.Core.Tools.ToolNames.CLOUDY_RECTANGULAR_AREA_MEASUREMENT,
        instance.Core.Tools.ToolNames.CLOUDY_RECTANGULAR_AREA_MEASUREMENT2,
        instance.Core.Tools.ToolNames.CLOUDY_RECTANGULAR_AREA_MEASUREMENT3,
        instance.Core.Tools.ToolNames.CLOUDY_RECTANGULAR_AREA_MEASUREMENT4,
    ];
    instance.UI.enableFeatures([instance.UI.Feature.Measurement, instance.UI.Feature.Initials]);
    instance.UI.disableTools(cloudyTools);

    // Set default toolbar group to Annotate
    instance.UI.setToolbarGroup('toolbarGroup-Annotate');

    // Set default tool on mobile devices to Pan.
    // https://apryse.atlassian.net/browse/WVR-3134
    if (isMobileDevice()) {
        instance.UI.setToolMode(instance.Core.Tools.ToolNames.PAN);
    }

    instance.Core.documentViewer.addEventListener('documentUnloaded', () => {
        if (searchParams.has('file')) {
            searchParams.delete('file');
            history.replaceState(null, '', '?' + searchParams.toString());
        }
    });

    instance.Core.annotationManager.enableAnnotationNumbering();

    instance.UI.NotesPanel.enableAttachmentPreview();

    // Add the demo-specific functionality
    customizeUI(instance).then(() => {
        // Create UI controls after demo is initialized
        createUIControls(instance);
    });
});

// Function to check if the user is on a mobile device
const isMobileDevice = () => {
    return (
        /(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|ipad|iris|kindle|Android|Silk|lge |maemo|midp|mmp|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows (ce|phone)|xda|xiino/i.test(
            window.navigator.userAgent
        ) ||
        /1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw-(n|u)|c55\/|capi|ccwa|cdm-|cell|chtm|cldc|cmd-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc-s|devi|dica|dmob|do(c|p)o|ds(12|-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(-|_)|g1 u|g560|gene|gf-5|g-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd-(m|p|t)|hei-|hi(pt|ta)|hp( i|ip)|hs-c|ht(c(-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i-(20|go|ma)|i230|iac( |-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|-[a-w])|libw|lynx|m1-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|-([1-8]|c))|phil|pire|pl(ay|uc)|pn-2|po(ck|rt|se)|prox|psio|pt-g|qa-a|qc(07|12|21|32|60|-[2-7]|i-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h-|oo|p-)|sdk\/|se(c(-|0|1)|47|mc|nd|ri)|sgh-|shar|sie(-|m)|sk-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h-|v-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl-|tdg-|tel(i|m)|tim-|t-mo|to(pl|sh)|ts(70|m-|m3|m5)|tx-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas-|your|zeto|zte-/i.test(
            window.navigator.userAgent.substring(0, 4)
        )
    );
}

// Cleanup function for when the demo is closed or page is unloaded
const cleanup = (instance) => {
    const { documentViewer } = instance.Core;
    const manager = documentViewer.getAccessibleReadingOrderManager();

    if (typeof instance !== 'undefined' &#x26;&#x26; instance.UI) {

        // Cleanup
        manager.endAccessibleReadingOrderMode();
        speechSynthesis.cancel();

        // Remove event listeners
        manager.removeEventListener('accessibleReadingOrderModeStarted', onAccessibleReadingOrderModeStarted);
        manager.removeEventListener('accessibleReadingOrderModeEnded', onAccessibleReadingOrderModeEnded);
        manager.removeEventListener('accessibleReadingOrderModeNoStructure', onAccessibleReadingOrderModeNoStructure);
        documentViewer.removeEventListener('documentLoaded', onDocumentLoaded);

        console.log('Cleaning up compare-files demo');
    }
};

// Register cleanup for page unload
window.addEventListener('beforeunload', () => cleanup());
window.addEventListener('unload', () => cleanup());

// UI section
// 
// Helper code to add controls to the viewer holding the buttons
// This code creates a container for the buttons, styles them, and adds them to the viewer
//

// Previous button
const prevButton = (instance) => {
    const button = document.createElement('button');
    button.className = 'btn btn-prev';
    button.textContent = 'Previous';
    button.disabled = true; // Initially disabled
    button.onclick = () => {
        previousElement(instance);
        updateUIControls();
    };

    return button;
};

// Next button
const nextButton = (instance) => {
    const button = document.createElement('button');
    button.className = 'btn btn-next';
    button.textContent = 'Next';
    button.disabled = true; // Initially disabled
    button.onclick = () => {
        nextElement(instance);
        updateUIControls();
    };
    
    return button;
};

// Audio button
const audioButton = (instance) => {
    const button = document.createElement('button');
    button.className = 'btn btn-audio';
    button.textContent = 'Mute';
    button.disabled = true; // Initially disabled
    button.onclick = () => {
        toggleMute(instance);
        if (isMuted) {
            button.textContent = 'Unmute';
        } else {
            button.textContent = 'Mute';
        }
    };

    return button;
};

// Untagged Document alert and Current page text
const currentPageText = () => {
    const wrapper = document.createElement('div');
    wrapper.className = 'current-page-text-wrapper';

    const untaggedDocumentAlert = document.createElement('div');
    untaggedDocumentAlert.className = 'untagged-document-alert';

    const untaggedDocumentAlertTitle = document.createElement('span');
    untaggedDocumentAlertTitle.className = 'untagged-document-alert-title';
    untaggedDocumentAlertTitle.textContent = 'UNTAGGED DOCUMENT';

    const untaggedDocumentAlertText = document.createElement('span');
    untaggedDocumentAlertText.className = 'untagged-document-alert-text';
    untaggedDocumentAlertText.textContent = 'No accessible tags or structure detected. Please upload a tagged document for the best accessible experience.';

    untaggedDocumentAlert.appendChild(untaggedDocumentAlertTitle);
    untaggedDocumentAlert.appendChild(untaggedDocumentAlertText);

    wrapper.appendChild(untaggedDocumentAlert);

    if (isAccessibleReadingOrderModeNoStructure) {
        untaggedDocumentAlert.classList.add('visible');
    }

    const currentPageText = document.createElement('span');
    currentPageText.className = 'current-page-text';
    currentPageText.textContent = `Current Page: ${currentPage}`;
    wrapper.appendChild(currentPageText);

    return wrapper;
};

// Text console
const textConsole = () => {
    const wrapper = document.createElement('div');
    wrapper.className = 'text-wrapper';

    const textArea = document.createElement('div');
    textArea.className = 'text-area';

    const textConsoleTitle = document.createElement('div');
    textConsoleTitle.className = 'text-console-title';
    textConsoleTitle.textContent = 'Text Console';

    textArea.appendChild(textConsoleTitle);

    const textContent = document.createElement('div');
    textContent.className = 'text-content';
    textContent.textContent = currentText ? currentText : 'No text is currently being read. Press "Next" to begin reading content.';

    textArea.appendChild(textContent);

    wrapper.appendChild(textArea);

    return wrapper;
};

const createUIControls = (instance) => {
    // Create a container for all controls (label, dropdown, and buttons)
    const controlsContainer = document.createElement('div');
    controlsContainer.className = 'controls-container';

    // Container for Buttons and Page Text
    const leftContainer = document.createElement('div');
    leftContainer.className = 'left-container';

    // Buttons Container
    const buttonsContainer = document.createElement('div');
    buttonsContainer.className = 'buttons-container';
    buttonsContainer.appendChild(prevButton(instance));
    buttonsContainer.appendChild(nextButton(instance));
    buttonsContainer.appendChild(audioButton(instance));
    leftContainer.appendChild(buttonsContainer);

    // Current Page Text
    leftContainer.appendChild(currentPageText());

    controlsContainer.appendChild(leftContainer);

    // Text Console
    const textConsoleElement = textConsole();
    controlsContainer.appendChild(textConsoleElement);

    element.insertBefore(controlsContainer, element.firstChild);

    updateUIControls();
};

const updateUIControls = () => {
    // Update the state of the buttons based on the current mode
    const nextButton = document.querySelector('.btn-next');
    if (nextButton) {
        nextButton.disabled = !isInAccessibleReadingOrderMode;
    }

    const prevButton = document.querySelector('.btn-prev');
    if (prevButton) {
        prevButton.disabled =
            !isInAccessibleReadingOrderMode ||
            !prevItem;
    }

    const audioButton = document.querySelector('.btn-audio');
    if (audioButton) {
        audioButton.disabled = !isInAccessibleReadingOrderMode;
    }

    // Show or hide the untagged document alert
    const untaggedDocumentAlert = document.querySelector('.untagged-document-alert');
    if (untaggedDocumentAlert) {
        if (isAccessibleReadingOrderModeNoStructure) {
            untaggedDocumentAlert.classList.add('visible');
        } else {
            untaggedDocumentAlert.classList.remove('visible');
        }
    }

    // Update the current page text
    const currentPageText = document.querySelector('.current-page-text');
    if (currentPageText) {
        currentPageText.textContent = `Current Page: ${currentPage}`;
    }

    // Update the text content in the text console
    const textContent = document.querySelector('.text-content');
    if (textContent) {
        textContent.textContent = currentText ? currentText : 'No text is currently being read. Press "Next" to begin reading content.';
    }
}
</code></pre>


---

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Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.apryse.com/web/get-started/samples/showcase-demo-accessible-reading-order.md?ask=<question>&goal=<endgoal>
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