+/**
+ * Replace characters or phrases within HTML elements only.
+ *
+ * @since 4.2.3
+ *
+ * @param string $haystack The text which has to be formatted.
+ * @param array $replace_pairs In the form array('from' => 'to', ...).
+ * @return string The formatted text.
+ */
+function wp_replace_in_html_tags( $haystack, $replace_pairs ) {
+ // Find all elements.
+ $comments =
+ '!' // Start of comment, after the <.
+ . '(?:' // Unroll the loop: Consume everything until --> is found.
+ . '-(?!->)' // Dash not followed by end of comment.
+ . '[^\-]*+' // Consume non-dashes.
+ . ')*+' // Loop possessively.
+ . '(?:-->)?'; // End of comment. If not found, match all input.
+
+ $regex =
+ '/(' // Capture the entire match.
+ . '<' // Find start of element.
+ . '(?(?=!--)' // Is this a comment?
+ . $comments // Find end of comment.
+ . '|'
+ . '[^>]*>?' // Find end of element. If not found, match all input.
+ . ')'
+ . ')/s';
+
+ $textarr = preg_split( $regex, $haystack, -1, PREG_SPLIT_DELIM_CAPTURE );
+ $changed = false;
+
+ // Optimize when searching for one item.
+ if ( 1 === count( $replace_pairs ) ) {
+ // Extract $needle and $replace.
+ foreach ( $replace_pairs as $needle => $replace );
+
+ // Loop through delimeters (elements) only.
+ for ( $i = 1, $c = count( $textarr ); $i < $c; $i += 2 ) {
+ if ( false !== strpos( $textarr[$i], $needle ) ) {
+ $textarr[$i] = str_replace( $needle, $replace, $textarr[$i] );
+ $changed = true;
+ }
+ }
+ } else {
+ // Extract all $needles.
+ $needles = array_keys( $replace_pairs );
+
+ // Loop through delimeters (elements) only.
+ for ( $i = 1, $c = count( $textarr ); $i < $c; $i += 2 ) {
+ foreach ( $needles as $needle ) {
+ if ( false !== strpos( $textarr[$i], $needle ) ) {
+ $textarr[$i] = strtr( $textarr[$i], $replace_pairs );
+ $changed = true;
+ // After one strtr() break out of the foreach loop and look at next element.
+ break;
+ }
+ }
+ }
+ }
+
+ if ( $changed ) {
+ $haystack = implode( $textarr );
+ }
+
+ return $haystack;
+}
+