JS - List unique font information of all DOM elements

listFontInformation.js

/**
 * List unique font information of all DOM elements
 * Based on the awesome code from AndrewRMinion
 * @see {@link https://gist.github.com/macbookandrew/f33dbbc0aa582d0515919dc5fb95c00a URL of the base code}
 *
 * @see {@link https://gist.github.com/ahoendgen/ebcabb595cc8465e4688275311a5c009/ URL for this file}
 *
 * @author AndrewRMinion Design (https://andrewrminion.com)
 * @author André Hoendgen (https://andre-hoendgen.de)
 * @version 1.1
 *
 * @license MIT
 * @copyright AndrewRMinion Design
 *
 * @example Show all unique font stacks in use on the current page
 *          console.table(fontsInPage());
 */

function fontsInPage() {
    // polyfill getComputedStyle
    if (typeof getComputedStyle == 'undefined') {
        getComputedStyle = function(elem) {
            return elem.currentStyle;
        };
    }

    // set vars
    var family,
        weight,
        style,
        key,
        thisNode,
        allStyles = {},
        nodes     = document.body.getElementsByTagName('*');

    // loop over all elements
    for (var i = 0; i < nodes.length; i++) {
        thisNode = nodes[i];

        if (thisNode.style) {

            family = thisNode.style.fontFamily || getComputedStyle(thisNode, '')['fontFamily'];
            weight = thisNode.style.fontWeight || getComputedStyle(thisNode, '')['fontWeight'];
            style  = thisNode.style.fontStyle || getComputedStyle(thisNode, '')['fontStyle'];

            if(family === undefined) {
                continue;
            }

            key = family + weight + style;

            // get element’s style
            if (allStyles[key] === undefined) {
                allStyles[key] = {
                    family,
                    weight,
                    style,
                };
            }

            // get element:before’s style
            family = getComputedStyle(thisNode, ':before')['fontFamily'];
            weight = getComputedStyle(thisNode, ':before')['fontWeight'];
            style  = getComputedStyle(thisNode, ':before')['fontStyle'];
            if (allStyles[key] === undefined) {
                allStyles[key] = {
                    family,
                    weight,
                    style,
                };
            }

            // get element:after’s style
            family = getComputedStyle(thisNode, ':after')['fontFamily'];
            weight = getComputedStyle(thisNode, ':after')['fontWeight'];
            style  = getComputedStyle(thisNode, ':after')['fontStyle'];
            if (allStyles[key] === undefined) {
                allStyles[key] = {
                    family,
                    weight,
                    style,
                };
            }
        }
    }
    return allStyles;
}

// console.table(fontsInPage());