detect-pdfjs-chromium.js

/**
 * Detects whether the PDF.js Chromium extension is installed in the browser.
 * Example: isPDFJSExtensionInstalled(function(result) { alert('Is PDF.js installed? ' + result);});
 *
 * @param {function(boolean)} callback - Called when the detection completed.
 *
 * Author: Rob Wu <rob@robwu.nl> (https://robwu.nl)
 *
 * Made synchronous by a handwaiving Lebbe
 * 
 * Public domain - all rights waived.
 */
function isPDFJSExtensionInstalledInChromium() {
        if (!window.chrome) {
            return false;
        }

        if(!chrome.webstore) {
            // pdf.js from Opera's addon gallery
            if(_isPDFJSExtensionInstalled('encfpfilknmenlmjemepncnlbbjlabkc')) return true;
        }

        // pdf.js from Chrome Web Store
        if(__isPDFJSExtensionInstalled('oemmndcbldboiebfnladdacbdfmadadm')) {
            return true;
        }

        return false;
     
        function _isPDFJSExtensionInstalled(id) {
            try {
                var x = new XMLHttpRequest();
                x.open('GET', 'chrome-extension://' + id + '/content/web/viewer.html', false);
                x.send(null);
                return x.status === 200;
            } catch (e) {
                return false;
            }
            return false;
        }
    };