# Search and Replace

## Overview

Run a search & replace on the page or pages on the prefix. This lets you apply simple changes to the page source. You can choose between string or regexp replacement.

![A sequence of search & replace rules on a prefix](../../img/dashboard2/path_settings_search_and_replace.png)

In the example above, search & replace is used to extend the list of classes (with a new class `foo`) for any element that possesses only the *hello-world* class.

![Using regexp backreferences](../../img/dashboard2/path_settings_search_and_replace_backreferences.jpg)

The replacement field supports regexp backreferences via the `$n` format, as in the screenshot above. The example looks for "**Hello World**" in the page source, stores backreferences to each letter group and reverses their order, resulting in the output "**World hello**".

Refer to the [`java.util.regex.Pattern` documentation](https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html) for the details of the supported regular expression format. 

Note that search & replace is a "naive" operation both for strings and regular expressions: HTML is not parsed, nor JavaScript evaluated at this stage (roughly, S&R runs as if it were working on a plain text source file). It cannot be used to solve recursive tasks.

**Multiple** S&R overrides can be added on the same prefix, and they will be applied *sequentially*. No two replacement strings/regexps may match, the dialog will display an error if you attempt to enter the same replacement rule twice.

## Parameters

+ _Content-types_: a pattern determining what content types the rule will apply to
+ _Search_ and _Replace_: patterns that determine replacements. If _Regexp_ is selected below, capture groups and backreferences may be used.
+ _Regexp_: treat the above patterns as regular expressions, enabling the use of cepture groups and other features.
+ _Target languages_: a pattern that determines which locales the rule will apply to. These patterns are applied to the locale codes (such as `de-DE`) and are case-sensitive! Omit to have the pattern apply to all locales.