Webpages change over time, and web archives hold copies of historical versions of webpages. Users of web archives, such as journalists, want to find and view changes on webpages over time. However, the current search interfaces for web archives do not support this task. For the web archives that include a full-text search feature, multiple versions of the same webpage that match the search query are shown individually without enumerating changes, or are grouped together in a way that hides changes. We present a change text search engine that allows users to find changes in webpages. We describe the implementation of the search engine backend and frontend, including a tool that allows users to view the changes between two webpage versions in context as an animation. We evaluate the search engine with U.S. federal environmental webpages that changed between 2016 and 2020. The change text search results page can clearly show when terms and phrases were added or removed from webpages. The inverted index can also be queried to identify salient and frequently deleted terms in a corpus.

翻译：网页随时间推移而变化，网络档案保存了网页的历史版本副本。记者等网络档案用户希望查找并查看网页随时间变化的内容。然而，当前网络档案的搜索接口并不支持此任务。对于包含全文搜索功能的网络档案而言，同一网页的多个版本在匹配搜索查询时会单独显示而不列举变化，或者被分组展示从而掩盖了变化。我们提出了一种变更文本搜索引擎，使用户能够查找网页中的变化。我们描述了该搜索引擎后端与前端的实现，包括一项工具，该工具允许用户以动画形式在上下文中查看两个网页版本之间的差异。我们使用2016年至2020年间发生变化的美国联邦环境网页对该搜索引擎进行了评估。变更文本搜索结果页面可清晰显示术语和短语何时被添加或从网页中删除。倒排索引还可用于查询语料库中显著且频繁被删除的术语。