Multi-Tab Support Showcase Demo Code Sample

Requirements

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

Web SDKLive demo

Easily launch and manage multiple documents concurrently with optimized performance across multiple tabs.

This demo allows you to:

• Load multiple PDFs in their own tab
• Edit each PDF file independently
• Download the updated PDFs

Implementation steps To add multi-tab capability to WebViewer:

Step 1: Get started with WebViewer in your preferred web stack 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.

// ES6 Compliant Syntax
// GitHub Copilot v1, Claude Sonnet 3.5, 2025-08-11
// File: multi-tab-support/index.js

import WebViewer from '@pdftron/webviewer';

const licenseKey = 'YOUR_WEBVIEWER_LICENSE_KEY';

const element = document.getElementById('viewer');
let theInstance = null;

const onLoad = async (instance) => {
  theInstance = instance;
  // Enable multi-tab support
  instance.UI.enableFeatures([instance.UI.Feature.MultiTab]);
  // Add default tabs
  instance.UI.TabManager.addTab(firstDefaultDocument.path, firstDefaultDocument.options);
  instance.UI.TabManager.addTab(secondDefaultDocument.path, secondDefaultDocument.options);
  instance.UI.TabManager.addTab(thirdDefaultDocument.path, thirdDefaultDocument.options);
  const allTabs = instance.UI.TabManager.getAllTabs();
  instance.UI.TabManager.setActiveTab(allTabs?.[0]?.id || 1);

  // Set up event listeners for tab management
  instance.UI.addEventListener(instance.UI.Events.TAB_ADDED, updateTabs);
  instance.UI.addEventListener(instance.UI.Events.TAB_DELETED, tabDeleted);
  instance.UI.addEventListener(instance.UI.Events.TAB_MOVED, tabMoved);
  instance.UI.addEventListener(instance.UI.Events.BEFORE_TAB_CHANGED, changeActiveTab);
  // Update the tabs UI (buttons to select and delete tabs)
  updateTabs();
  // Add the Add Tab button at the end of the controls container
  controlsContainer.appendChild(buttonNewTab);
};

WebViewer(
  {
    path: '/lib',
    licenseKey: licenseKey, 
    enableFilePicker: true, // Enable file picker to open files. In WebViewer -> menu icon -> Open File
  },
  element
).then((instance) => {
  onLoad(instance);
});

// UI elements corresponding to document tabs
// Each tab will have a button to select (activate) it and a button to delete it
let tabButtons = [];

// preserve the active tab ID to restore the active tab after deletion or movement
let activeTabID = -1; // -1 means no active tab

// listener for moving tab event
function tabMoved() {
  activeTabID = theInstance.UI.TabManager.getActiveTab().id;
  updateTabs();
}

// listener for tab deletion
function tabDeleted(){
  const tabManager = theInstance.UI.TabManager;
  try {
    activeTabID = tabManager.getActiveTab().id; // preserve the active tab ID if it exists
  } catch (error) {
    activeTabID = -1; // if the user deletes the active tab, we reset the active tab ID
  }
  updateTabs();
  const allTabs = tabManager.getAllTabs()
  if(allTabs.length > 1) { //force refreshing after deletion
    const saveActiveTabID = tabManager.getActiveTab().id;
    allTabs.forEach(tab => {
      if(tab.id != saveActiveTabID) {
        tabManager.setActiveTab(tab.id);
      }
    });
    tabManager.setActiveTab(saveActiveTabID);
  }
}

// common function to update the tab buttons in the UI
// This function will be called for any change affecting tabs, which includes:
// 1. After default tabs are created
// 2. When the active tab changes
// 3. When a tab is added, deleted, or moved
function updateTabs(){
  // Remove all tab elements from container and reset the array
  // Rebuilding the buttons array is an easy way to keep the buttons in sync with the tabs
  tabButtons.forEach(element => element.remove());
  tabButtons = [];
  const tabManager = theInstance.UI.TabManager;
  const allTabs = tabManager.getAllTabs();
  
  allTabs.forEach(tab => {
    // Create a button to select the tab (make it active)
    const buttonSelectTab = document.createElement('button');
    tabButtons.push(buttonSelectTab);
    buttonSelectTab.textContent = tab.options.filename;
    buttonSelectTab.className = 'btn-select';
    // The container inlucdes a line break to separate the tab buttons from the AddTab button.
    // Insert the button before the line break
    controlsContainer.insertBefore(buttonSelectTab, lineBreak);
    // Add an event handler to select the tab when clicked
    buttonSelectTab.onclick = async () => {
      theInstance.UI.TabManager.setActiveTab(tab.id);
    };
    // Create a button to delete the tab
    const buttonDelTab = document.createElement('button');
    tabButtons.push(buttonDelTab);
    buttonDelTab.textContent = 'x';
    buttonDelTab.className = 'btn-del';
    controlsContainer.insertBefore(buttonDelTab, lineBreak);
    // Add an event handler to delete the tab when clicked
    buttonDelTab.onclick = async () => {
      activeTabID = theInstance.UI.TabManager.getActiveTab().id;
      theInstance.UI.TabManager.deleteTab(tab.id);
    };
  });

  if(allTabs.length < 1)
    return; // No tabs to display
  
  let activeTabIndex = 0;
  if(activeTabID < 0) // if no active tab ID is preserved, try to find the active tab
  {
    try{
      activeTabIndex = allTabs.indexOf(tabManager.getActiveTab());
    } catch (error){
      // activeTabIndex will remain 0 if no active tab is found
    }
  } else {
    // If we have an active tab ID, find its index and set the button class accordingly
    activeTabIndex = allTabs.findIndex(obj => obj.id === activeTabID);
  }
  // Set the button styles based on the active tab index
  setButtonStyles(activeTabIndex);
}

// Function to set styles for the tab buttons based on the active tab index
// This function will be called whenever the active tab changes or tabs are added/deleted/moved
// It updates the class of the buttons to indicate which tab is active
function setButtonStyles(activeTabIndex) {
  tabButtons.forEach((button, index) => {
    if(index % 2 === 0){ // Only update the select buttons (even indices)
      button.className = (activeTabIndex * 2 === index) ? 'btn-active' : 'btn-select';
    }
  });
}

// Listener for tab change events
function changeActiveTab(prevTab, nextTab) {
  if (activeTabID === nextTab.id) 
    return;

  activeTabID = nextTab.id;
  const allTabs = theInstance.UI.TabManager.getAllTabs();
  const activeTabIndex = allTabs.findIndex(tab => tab.id === activeTabID);
  setButtonStyles(activeTabIndex);
}

// default documents to load
const firstDefaultDocument = {
  path: 'https://apryse.s3.amazonaws.com/public/files/samples/WebviewerDemoDoc.pdf',
  options: {
    extension: 'pdf',
    filename: 'Demo PDF',
    setActive: true,
    saveCurrentActiveTabState: true,
  },
};

const secondDefaultDocument = {
  path: 'https://apryse.s3.amazonaws.com/public/files/samples/sales_tracker.xlsx',
  options: {
    extension: 'xlsx',
    filename: 'Sales Tracker (xlsx)',
    setActive: false,
    saveCurrentActiveTabState: false,
  },
};

const thirdDefaultDocument = {
  path: 'https://apryse.s3.amazonaws.com/public/files/samples/Jupiter_Poster_Raster.png',
  options: {
    extension: 'png',
    filename: 'Jupiter Poster (PNG)',
    setActive: false,
    saveCurrentActiveTabState: false,
  },
};

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

const buttonNewTab = document.createElement('button');
buttonNewTab.textContent = 'Add New Tab';

buttonNewTab.onclick = async () => {
  theInstance.UI.openElements(['OpenFileModal']);
};

// Create a break element to separate controls into two lines
const lineBreak = document.createElement('br');

// Create a container for all controls (label, dropdown, and buttons)
const controlsContainer = document.createElement('div');

buttonNewTab.className = 'btn-style';

controlsContainer.className = 'control-container';
controlsContainer.appendChild(lineBreak);
element.insertBefore(controlsContainer, element.firstChild);