This counts up all the words (innerText) at each level of the dom tree.

count-dom-words.js

// Procedure:
countWords(document.body);



/*
 * Count the text inside each element.
 * Parents include all the words of their children.
 * Additionally, notes how much of the text comes "before" this node in depth-first dom order.
 * 
 * The purpose of this was to find which subtrees of the dom have most of the text.
 * 
 * The output looks like:
 
  "div: 8264 (22.55%) inside. 433 (1.19%) before)": [
      "p: 292 (0.8%) inside. 433 (1.19%) before)": [
          "span: 72 (0.2%) inside. 433 (1.19%) before)": []
          "span: 119 (0.33%) inside. 505 (1.38%) before)": []
          "a: 21 (0.06%) inside. 624 (1.71%) before)": [
              "span: 21 (0.06%) inside. 624 (1.71%) before)": []
          "span: 77 (0.22%) inside. 645 (1.76%) before)": []

 */
function countWords(el, max = el.innerText.length, charsSeen = 0) {
    if (shouldStop(el)) {
        return;
    }

    const innerText = cleanText(el);
    const len = innerText.length;

    // If there aren't many letters, show them; otherwise show a count
    const desc = (len > 0 && len < 42)
        ? `'${innerText}'`
        : len;

    // What % of total text does this node have under it?
    const inside = toPercent(len/max);

    const label = `${nameOf(el)}: ${desc} (${inside}%) inside. ${charsSeen} (${toPercent(charsSeen/max)}%) before)`

    el.setAttribute('title', label);
    
    const kidStats = [];
    for (let kid of Array.from(el.children)) {
        const stats = countWords(kid, max, charsSeen); // Recurse
        if (!stats) { continue; }
        kidStats.push(stats);
        charsSeen += cleanText(kid).length;
    }

    return { [label]: kidStats };
}

function nameOf(el) {
    return `${el.tagName.toLowerCase()}`;
}



function shouldStop(el) {
    if (el == null) { return true; }

    // Is one of the non-content tags
    const tagsWithNoContent = ['SCRIPT', 'IMG']; // TODO: save image paths
    if (tagsWithNoContent.includes(el.tagName)) { return true; }
    
    // Contains no text
    if (el.innerText == null || el.innerText.length === 0) { return true; }
    
    return false;
}

function cleanText(el = {}) {
    return (el.innerText || '').trim();
}

// Show a percentage rounded to two decimal places
function toPercent(decimal) {
    return Math.ceil(decimal * 10000) / 100
}