git pre-commit hook that checks for debugger / console.log

pre-commit.sh

#!/bin/sh
#
# An example hook script to verify what is about to be committed.
# Called by git-commit with no arguments.  The hook should
# exit with non-zero status after issuing an appropriate message if
# it wants to stop the commit.
#
# To enable this hook, make this file executable.

if git-rev-parse --verify HEAD 2>/dev/null
then
  git-diff-index -p -M --cached HEAD --
else
  # NEEDSWORK: we should produce a diff with an empty tree here
  # if we want to do the same verification for the initial import.
  :
fi |
perl -e '
# eslint airbnb config is pretty good at catching most of errors
# prettier is pretty good at maintaining consitent code formatting
# this script is solely needed to catch console.log and debug statements
my $found_bad = 0;
my $filename;
my $reported_filename = "";
my $lineno;

sub bad_line {
  my ($why, $line) = @_;
  if (!$found_bad) {
    print STDERR "* [debug pre-commit] You have some suspicious patch lines:\n";
    print STDERR "*\n";
    $found_bad = 1;
  }
  if ($reported_filename ne $filename) {
    print STDERR "* In $filename\n";
    $reported_filename = $filename;
  }
  print STDERR "* $why (line $lineno)\n";
  print STDERR "$filename:$lineno:$line\n";
}

$last_line = "";
while (<>) {
  if (m|^diff --git a/(.*) b/\1$|) {
    $filename = $1;
    next;
  }
  if (/^@@ -\S+ \+(\d+)/) {
    $lineno = $1 - 1;
    next;
  }
  if (/^ /) {
    $lineno++;
    next;
  }
  if (s/^\+//) {
    $lineno++;
    chomp;
    if (/debug/) {
      bad_line("debug statement/import left in", $_);
    }
    if (/debugFn/) {
      bad_line("debugFn statement left in", $_);
    }
    if (/log/) {
      bad_line("log statement left in", $_);
    }
  }
}
exit($found_bad);
'