A gist that feeds diffs into a variable for precommit checks.

diff.sh

# Determine modified and staged files.
JSSTAGED=$(git --no-pager diff --relative --name-only --cached --diff-filter=d -- '**/*.js' \
    | xargs -L 1 printf "%s/%s\n" "$PWD")
PHPSTAGED=$(git --no-pager diff --relative --name-only --cached --diff-filter=d -- '**/*.php' \
    | xargs -L 1 printf "%s/%s\n" "$PWD")
CSSSTAGED=$(git --no-pager diff --relative --name-only --cached --diff-filter=d -- '**/*.css' \
    | xargs -L 1 printf "%s/%s\n" "$PWD")
SCSSSTAGED=$(git --no-pager diff --relative --name-only --cached --diff-filter=d -- '**/*.scss' \
    | xargs -L 1 printf "%s/%s\n" "$PWD")
TSSTAGED=$(git --no-pager diff --relative --name-only --cached --diff-filter=d -- '**/*.ts' '**/*.tsx' \
    | xargs -L 1 printf "%s/%s\n" "$PWD")
Then feed the vars into the sniffers:
if [ ! -z "$JSSTAGED" ]; then
	yarn --cwd $(git rev-parse --show-toplevel)/src eslint $JSSTAGED
fi