Xah Talk Show 2022-09-21 Emacs Lisp Coding, Write Command to Demote HTML Headers

• Elisp: Find Replace String in Buffer

• JS: Sparse Array

(defun xah-html-demote-header-h2h3h4h5 ()
  "Demote HTML headers in whole buffer.
except h1. others, h2 becomes h3, etc. And h6 remains the same.
Version 2022-09-21"
  (interactive)
  (let ((case-fold-search nil))
    (save-excursion
      (progn
        (goto-char (point-min))
        (while (search-forward "<h5>" nil t)
          (replace-match "<h6>"))
        (goto-char (point-min))
        (while (search-forward "</h5>" nil t)
          (replace-match "</h6>")))
      (progn
        (goto-char (point-min))
        (while (search-forward "<h4>" nil t)
          (replace-match "<h5>"))
        (goto-char (point-min))
        (while (search-forward "</h4>" nil t)
          (replace-match "</h5>")))
      (progn
        (goto-char (point-min))
        (while (search-forward "<h3>" nil t)
          (replace-match "<h4>"))
        (goto-char (point-min))
        (while (search-forward "</h3>" nil t)
          (replace-match "</h4>")))
      (progn
        (goto-char (point-min))
        (while (search-forward "<h2>" nil t)
          (replace-match "<h3>"))
        (goto-char (point-min))
        (while (search-forward "</h2>" nil t)
          (replace-match "</h3>"))))))