Regex search and replace text within an HTML document that is not part of a tag

regex-html-text-only

/**
 * the [^<i] at the end of the first capture prevents the regex from catching strings
 * that are actually part of other strings or tags.  Replace the 'i' with anything that
 * shouldn't come before the text to be captured.  Example: capture 'nSPEC' but not
 * 'inspect' -- hence the 'i'.
 *
 * the [^™] in the third capture does similarly for what comes after the text to be captured.
 */
$input = preg_replace('/>(?P<before>[^<]*?[^<i])?(?P<theText>The text goes here)(?P<char>[^™])/i', ">$1<span class=\"nspec\">$2™</span>$3", $input);