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The Search-and-Replace Regex with VS Code is simply using JavaScript's regular expressions as specified in ECMAScript 5 (the runtime of VS Code) VS Code has the option to opt into using the Perl based PCRE2 engine. This allows more advanced regex operations like lookaheads and backreferences. Press Ctrl + H on Windows and Linux, or ⌥⌘F on Mac to enable search and replace tool. The find widget can be enabled by setting search.usePCRE2.