Javascript Regex Lookbehind not working

[msilberg]

Issue Type: Bug

Unfortunately Vscode does not suppport Regex with neither negative nor positive lookbehinds (e.g. (?<=.) ). It always marks it as incorrect.

VS Code version: Code 1.37.0 (036a6b1, 2019-08-08T01:24:14.598Z)
OS version: Linux x64 5.0.0-23-generic

System Info

Item	Value
CPUs	Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz (8 x 2934)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: disabled_software oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: disabled_software skia_deferred_display_list: disabled_off skia_renderer: disabled_off surface_synchronization: enabled_on video_decode: unavailable_off viz_display_compositor: disabled_off webgl: enabled webgl2: enabled
Load (avg)	1, 1, 1
Memory (System)	15.43GB (3.98GB free)
Process Argv	--unity-launch
Screen Reader	no
VM	0%

[vscodebot]

(Experimental duplicate detection)
Thanks for submitting this issue. Please also check if it is already covered by an existing one, like:

• Trying to Search using variable length look-behind suggests enabling search.usePCRE2, but no such setting (#79109)
• [REGEX] Non fixed-length lookbehind support (#76502)

[gjsjohnmurray]

According to #70156 these aren't supported in PCRE2, which is what VSCode uses.

[IllusionMH]

@msilberg if you perform Find (in current file) than JS RegExp engine is used and it supports non-fixed length lookbehind.
However Find in Files uses ripgrep and its engine supports only fixed length lookbehind expression.

Adding better error message and hiding incorrect notification is tracked in #79109

/duplicate #79109

UPD. If you have problem with Find (in current file) or you are sure that you use PCRE2 compatible expression in Find in Files - please provide more details.

[vscodebot]

Thanks for creating this issue! We figured it's covering the same as another one we already have. Thus, we closed this one as a duplicate. You can search for existing issues here. See also our issue reporting guidelines.

Happy Coding!