format numbers on the page with commas

format.js

var ignoreNodes = new Set(['INPUT', 'TEXTAREA']);
function walk(node) {
  if (ignoreNodes.has(node.tagName)) {
    return;
  }
  switch (node.nodeType) {
    // Element
    case 1:
    // Document
    case 9:
    // Document fragment
    case 11: {
      let next, child = node.firstChild;
      while (child !== null) {
        next = child.nextSibling;
        walk(child);
        child = next;
      }
      break;
    }
    // Text node
    case 3: {
      node.nodeValue = node.nodeValue.replace(/(^\d*\.?\d+$)+/g, function replacer(match) {
        return new Intl.NumberFormat('en-US').format(match)
      })
      break;
    }    
  }
}
walk(document.body)