Detect available fonts with JS

detect-available-fonts.js

/**
 * JavaScript code to detect available availability of a
 * particular font in a browser using JavaScript and CSS.
 *
 * Author : Lalit Patel
 * Website: http://www.lalit.org/lab/javascript-css-font-detect/
 * License: Apache Software License 2.0
 *          http://www.apache.org/licenses/LICENSE-2.0
 * Version: 0.15 (21 Sep 2009)
 *          Changed comparision font to default from sans-default-default,
 *          as in FF3.0 font of child element didn't fallback
 *          to parent element if the font is missing.
 * Version: 0.2 (04 Mar 2012)
 *          Comparing font against all the 3 generic font families ie,
 *          'monospace', 'sans-serif' and 'sans'. If it doesn't match all 3
 *          then that font is 100% not available in the system
 * Version: 0.3 (24 Mar 2012)
 *          Replaced sans with serif in the list of baseFonts
 */

/**
 * Usage: d = new FontDetector();
 *        d.detect('font name');
 */
var FontDetector = function() {
    // a font will be compared against all the three default fonts.
    // and if it doesn't match all 3 then that font is not available.
    var baseFonts = ['monospace', 'sans-serif', 'serif'];

    //we use m or w because these two characters take up the maximum width.
    // And we use a LLi so that the same matching fonts can get separated
    var testString = "mmmmmmmmmmlli";

    //we test using 72px font size, we may use any size. I guess larger the better.
    var testSize = '72px';

    var h = document.getElementsByTagName("body")[0];

    // create a SPAN in the document to get the width of the text we use to test
    var s = document.createElement("span");
    s.style.fontSize = testSize;
    s.innerHTML = testString;
    var defaultWidth = {};
    var defaultHeight = {};
    for (var index in baseFonts) {
        //get the default width for the three base fonts
        s.style.fontFamily = baseFonts[index];
        h.appendChild(s);
        defaultWidth[baseFonts[index]] = s.offsetWidth; //width for the default font
        defaultHeight[baseFonts[index]] = s.offsetHeight; //height for the defualt font
        h.removeChild(s);
    }

    function detect(font) {
        var detected = false;
        for (var index in baseFonts) {
            s.style.fontFamily = '"' + font + '"' + ',' + baseFonts[index]; // name of the font along with the base font for fallback.
            h.appendChild(s);
            var matched = (s.offsetWidth != defaultWidth[baseFonts[index]] || s.offsetHeight != defaultHeight[baseFonts[index]]);
            h.removeChild(s);
            detected = detected || matched;
        }
        return detected;
    }

    this.detect = detect;
};

I'd change

document.getElementsByTagName("body")[0];

to

document.body;

I'd change

document.getElementsByTagName("body")[0];

to

document.body;

Is this code supposed to work? I tried it in jsfiddle (https://jsfiddle.net/sekwxLg4/) but the run area stays empty

It works for Arial: // example f = new FontDetector() console.log('detect', f.detect('Arial')) Regards, Gabe.

…

------ Gabiriele Lalasava Founder - Seedess P2P Video Streaming https://seedess.com/ +1 (323) 454-3430 ***@***.***

On Tue, Nov 2, 2021 at 5:17 PM sfederici ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ I'd change document.getElementsByTagName("body")[0]; to document.body; Is this code supposed to work? I tried it in jsfiddle ( https://jsfiddle.net/sekwxLg4/) but the run area stays empty — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <https://gist.github.com/3b0bf8e88ceef7518844#gistcomment-3948260>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAGFQMYEMIAJKD2XLQ74MKDUJ6UDXANCNFSM4MEIBW2Q> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

Could we use WebGL to detect fonts without blocking main DOM context?