diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 44940d1..fd62050 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -66,3 +66,22 @@ jobs:
       - name: Run Python tests
         run: |
           for suite in tests/python/*/run.sh; do "$suite"; done
+
+  javascript-tests:
+    name: JavaScript Tests
+    runs-on: ubuntu-latest
+    needs: shellcheck
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Prepare test environment
+        run: |
+          chmod +x javascript/*.sh
+          chmod +x tests/lib/*.bash
+          find tests/javascript -name "*.sh" -exec chmod +x {} +
+
+      - name: Run JavaScript tests
+        run: |
+          for suite in tests/javascript/*/run.sh; do "$suite"; done
diff --git a/javascript/check_eslint_all.sh b/javascript/check_eslint_all.sh
new file mode 100755
index 0000000..6b74025
--- /dev/null
+++ b/javascript/check_eslint_all.sh
@@ -0,0 +1,27 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs ESLint with --fix on the entire project (app/, components/, lib/, types/).
+# No file arguments required — always checks all configured directories.
+# Exits 1 if ESLint fails to fix issues, 0 on success.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+cd "$PROJECT_ROOT"
+
+# Directories to check
+LINT_DIRS=("app/" "components/" "lib/" "types/")
+
+echo "=== ESLint (full project) ==="
+
+echo "Fixing ESLint issues..."
+if ! npx eslint "${LINT_DIRS[@]}" --fix; then
+    echo "ERROR: Failed to fix ESLint issues"
+    exit 1
+fi
+echo "ESLint issues fixed!"
+
+exit 0
diff --git a/javascript/check_prettier.sh b/javascript/check_prettier.sh
new file mode 100755
index 0000000..ad9f06c
--- /dev/null
+++ b/javascript/check_prettier.sh
@@ -0,0 +1,44 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs Prettier --write on staged TypeScript files.
+# Receives files to check as arguments: ./check_prettier.sh file1.ts file2.ts
+# Exits 1 if Prettier fails, 0 on success. Skips if no .ts files provided.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+cd "$PROJECT_ROOT"
+
+# Parse arguments
+FILES=()
+
+# Filter only .ts files
+RELEVANT_FILES=()
+for file in "${FILES[@]}"; do
+    if [[ "$file" == *.ts ]]; then
+        if [ -f "$file" ]; then
+            RELEVANT_FILES+=("$file")
+        fi
+    fi
+done
+
+# Skip if no relevant files
+if [ ${#RELEVANT_FILES[@]} -eq 0 ]; then
+    echo "=== Code Style Check ==="
+    echo "No TypeScript files to check, skipping..."
+    exit 0
+fi
+
+echo "=== Code Style Check (${#RELEVANT_FILES[@]} files) ==="
+
+echo "Fixing code style issues..."
+if ! npx prettier --write "${RELEVANT_FILES[@]}"; then
+    echo "ERROR: Failed to fix code style"
+    exit 1
+fi
+echo "Code style fixed!"
+
+exit 0
diff --git a/javascript/check_prettier_all.sh b/javascript/check_prettier_all.sh
new file mode 100755
index 0000000..6afa777
--- /dev/null
+++ b/javascript/check_prettier_all.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs Prettier --write on all TypeScript files in the project.
+# No file arguments required — uses glob patterns for app/, components/, lib/, etc.
+# Exits 1 if Prettier fails, 0 on success.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+cd "$PROJECT_ROOT"
+
+echo "Fixing code style issues..."
+if ! npx prettier --write "app/**/*.{ts,tsx}" "components/**/*.{ts,tsx}" "lib/**/*.ts" "services/**/*.ts" "types/**/*.ts"; then
+    echo "ERROR: Failed to fix code style"
+    exit 1
+fi
+echo "Code style fixed!"
+
+exit 0
diff --git a/javascript/check_test_coverage.sh b/javascript/check_test_coverage.sh
new file mode 100755
index 0000000..58a161d
--- /dev/null
+++ b/javascript/check_test_coverage.sh
@@ -0,0 +1,89 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs vitest with optional --watch and --coverage flags for specified files.
+# Receives files as arguments: ./check_test_coverage.sh file1.ts [--watch] [--coverage]
+# Exits 1 if tests fail, 0 on success. Runs full suite when no files provided.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../../.." && pwd)"
+
+cd "$PROJECT_ROOT"
+
+# Parse arguments
+WATCH=false
+COVERAGE=false
+FILES=()
+
+for arg in "$@"; do
+    case $arg in
+        --watch)
+            WATCH=true
+            ;;
+        --coverage)
+            COVERAGE=true
+            ;;
+        *)
+            FILES+=("$arg")
+            ;;
+    esac
+done
+
+# Filter only test files or source files that have tests
+RELEVANT_FILES=()
+for file in "${FILES[@]}"; do
+    if [[ "$file" == *.ts ]]; then
+        if [ -f "$file" ]; then
+            RELEVANT_FILES+=("$file")
+        fi
+    fi
+done
+
+# Determine test command
+if [ ${#RELEVANT_FILES[@]} -eq 0 ]; then
+    echo "=== Tests (full suite) ==="
+
+    if [ "$WATCH" = true ]; then
+        echo "Running tests in watch mode..."
+        npx vitest
+    elif [ "$COVERAGE" = true ]; then
+        echo "Running tests with coverage..."
+        if ! npx vitest run --coverage; then
+            echo "ERROR: Tests failed"
+            exit 1
+        fi
+        echo "Tests passed with coverage!"
+    else
+        echo "Running tests..."
+        if ! npx vitest run; then
+            echo "ERROR: Tests failed"
+            exit 1
+        fi
+        echo "Tests passed!"
+    fi
+else
+    echo "=== Tests (related to ${#RELEVANT_FILES[@]} changed files) ==="
+
+    if [ "$WATCH" = true ]; then
+        echo "Running related tests in watch mode..."
+        npx vitest --related "${RELEVANT_FILES[@]}"
+    elif [ "$COVERAGE" = true ]; then
+        echo "Running related tests with coverage..."
+        if ! npx vitest run --related "${RELEVANT_FILES[@]}" --coverage; then
+            echo "ERROR: Tests failed"
+            exit 1
+        fi
+        echo "Tests passed with coverage!"
+    else
+        echo "Running related tests..."
+        if ! npx vitest run --related "${RELEVANT_FILES[@]}"; then
+            echo "ERROR: Tests failed"
+            exit 1
+        fi
+        echo "Tests passed!"
+    fi
+fi
+
+exit 0
diff --git a/javascript/check_tests.sh b/javascript/check_tests.sh
new file mode 100755
index 0000000..f14d959
--- /dev/null
+++ b/javascript/check_tests.sh
@@ -0,0 +1,77 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs vitest for changed TypeScript files or from git staged files.
+# Receives files as arguments: ./check_tests.sh file1.ts file2.ts
+# Exits 1 if tests fail, 0 on success. Skips files matching SKIP_PATTERNS.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+cd "$PROJECT_ROOT"
+
+# Patterns to skip
+SKIP_PATTERNS=("tests/" ".test.ts" ".config.ts" ".config.mjs" "types/" ".d.ts" "layout.tsx" "page.tsx" "loading.tsx" "error.tsx" "globals.css" "providers/" "components/ui/" "prisma/")
+
+should_skip() {
+    local file="$1"
+    for pattern in "${SKIP_PATTERNS[@]}"; do
+        [[ "$file" == *"$pattern"* ]] && return 0
+    done
+    return 1
+}
+
+# Get test path: source.ts -> tests/source.test.ts
+get_test_path() {
+    local file="$1"
+    local base="${file%.ts}"
+    base="${base%.tsx}"
+    echo "tests/${base}.test.ts"
+}
+
+# Get files to check
+FILES=()
+if [ $# -eq 0 ]; then
+    while IFS= read -r line; do
+        [[ "$line" == *.ts || "$line" == *.tsx ]] && FILES+=("$line")
+    done < <(git diff --cached --name-only --diff-filter=ACM 2>/dev/null || true)
+    [ ${#FILES[@]} -eq 0 ] && echo "No staged TypeScript files" && exit 0
+else
+    for arg in "$@"; do
+        [[ "$arg" == *.ts || "$arg" == *.tsx ]] && FILES+=("$arg")
+    done
+fi
+
+# Collect tests to run
+TESTS_TO_RUN=()
+
+for file in "${FILES[@]}"; do
+    [ ! -f "$file" ] && continue
+
+    # If it's already a test file, add it directly
+    if [[ "$file" == *.test.ts ]]; then
+        [ -f "$file" ] && TESTS_TO_RUN+=("$file")
+        continue
+    fi
+
+    should_skip "$file" && continue
+
+    test_path=$(get_test_path "$file")
+    [ -f "$test_path" ] && TESTS_TO_RUN+=("$test_path")
+done
+
+# Remove duplicates
+mapfile -t TESTS_TO_RUN < <(printf '%s\n' "${TESTS_TO_RUN[@]}" | sort -u)
+
+if [ ${#TESTS_TO_RUN[@]} -eq 0 ]; then
+    echo "No tests to run for changed files"
+    exit 0
+fi
+
+echo "=== Running tests for changed files ==="
+echo "Tests: ${TESTS_TO_RUN[*]}"
+echo ""
+
+npx vitest run "${TESTS_TO_RUN[@]}"
diff --git a/javascript/check_tests_all.sh b/javascript/check_tests_all.sh
new file mode 100755
index 0000000..7d91b9d
--- /dev/null
+++ b/javascript/check_tests_all.sh
@@ -0,0 +1,18 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs the full vitest test suite for the project.
+# No file arguments required — runs all tests via `npx vitest run`.
+# Exits 1 if tests fail, 0 on success.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+cd "$PROJECT_ROOT"
+
+echo "=== Running tests ==="
+echo ""
+
+npx vitest run
diff --git a/javascript/check_tests_exist.sh b/javascript/check_tests_exist.sh
new file mode 100755
index 0000000..689e4f0
--- /dev/null
+++ b/javascript/check_tests_exist.sh
@@ -0,0 +1,78 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Checks that each staged TypeScript source file has a corresponding test file.
+# Receives files as arguments or reads from git staged files if none provided.
+# Exits 1 if any source file is missing its tests/...test.ts counterpart.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+cd "$PROJECT_ROOT"
+
+# Patterns to skip (no tests required)
+SKIP_PATTERNS=("tests/" ".test.ts" ".config.ts" ".config.mjs" "types/" ".d.ts" "layout.tsx" "page.tsx" "loading.tsx" "error.tsx" "globals.css" "providers/" "components/ui/" "prisma/")
+
+should_skip() {
+    local file="$1"
+    for pattern in "${SKIP_PATTERNS[@]}"; do
+        [[ "$file" == *"$pattern"* ]] && return 0
+    done
+    return 1
+}
+
+# Get test path: source.ts -> tests/source.test.ts
+get_test_path() {
+    local file="$1"
+    local base="${file%.ts}"
+    base="${base%.tsx}"
+    echo "tests/${base}.test.ts"
+}
+
+# Get files to check
+FILES=()
+if [ $# -eq 0 ]; then
+    while IFS= read -r line; do
+        [[ "$line" == *.ts || "$line" == *.tsx ]] && FILES+=("$line")
+    done < <(git diff --cached --name-only --diff-filter=ACM 2>/dev/null || true)
+    [ ${#FILES[@]} -eq 0 ] && echo "No staged TypeScript files" && exit 0
+else
+    for arg in "$@"; do
+        [[ "$arg" == *.ts || "$arg" == *.tsx ]] && FILES+=("$arg")
+    done
+fi
+
+echo "=== Test Coverage Check ==="
+echo ""
+
+missing=()
+found=()
+skipped=()
+
+for file in "${FILES[@]}"; do
+    [ ! -f "$file" ] && continue
+    should_skip "$file" && { skipped+=("$file"); continue; }
+
+    test_path=$(get_test_path "$file")
+
+    if [ -f "$test_path" ]; then
+        found+=("$file")
+    else
+        missing+=("$file → $test_path")
+    fi
+done
+
+[ ${#found[@]} -gt 0 ] && echo -e "Has tests:" && printf '  %s\n' "${found[@]}" && echo ""
+[ ${#skipped[@]} -gt 0 ] && echo -e "Skipped:" && printf '  %s\n' "${skipped[@]}" && echo ""
+
+if [ ${#missing[@]} -gt 0 ]; then
+    echo -e "Missing tests:"
+    printf '  %s\n' "${missing[@]}"
+    echo ""
+    echo -e "ERROR: ${#missing[@]} file(s) missing tests"
+    exit 1
+fi
+
+echo -e "All files have tests!"
diff --git a/javascript/check_tsc_all.sh b/javascript/check_tsc_all.sh
new file mode 100755
index 0000000..38fa34f
--- /dev/null
+++ b/javascript/check_tsc_all.sh
@@ -0,0 +1,26 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs TypeScript type checking on the entire project using tsconfig.check.json.
+# No file arguments required — checks all files configured in tsconfig.
+# Exits 1 if type check fails, 0 on success.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+cd "$PROJECT_ROOT"
+
+# TypeScript config
+TS_CONFIG="tsconfig.check.json"
+
+echo "=== TypeScript ==="
+echo "Running type check..."
+if ! npx tsc --project "$TS_CONFIG"; then
+    echo "ERROR: TypeScript check failed"
+    exit 1
+fi
+echo "TypeScript check passed!"
+
+exit 0
diff --git a/javascript/check_vitest.sh b/javascript/check_vitest.sh
new file mode 100755
index 0000000..2be1340
--- /dev/null
+++ b/javascript/check_vitest.sh
@@ -0,0 +1,89 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs vitest for specified files or the full suite. Supports --watch and --coverage.
+# Receives files as arguments: ./check_vitest.sh file1.ts [--watch] [--coverage]
+# Exits 1 if tests fail, 0 on success. Runs full suite when no files provided.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+cd "$PROJECT_ROOT"
+
+# Parse arguments
+WATCH=false
+COVERAGE=false
+FILES=()
+
+for arg in "$@"; do
+    case $arg in
+        --watch)
+            WATCH=true
+            ;;
+        --coverage)
+            COVERAGE=true
+            ;;
+        *)
+            FILES+=("$arg")
+            ;;
+    esac
+done
+
+# Filter only test files or source files that have tests
+RELEVANT_FILES=()
+for file in "${FILES[@]}"; do
+    if [[ "$file" == *.ts ]]; then
+        if [ -f "$file" ]; then
+            RELEVANT_FILES+=("$file")
+        fi
+    fi
+done
+
+# Determine test command
+if [ ${#RELEVANT_FILES[@]} -eq 0 ]; then
+    echo "=== Tests (full suite) ==="
+
+    if [ "$WATCH" = true ]; then
+        echo "Running tests in watch mode..."
+        npx vitest
+    elif [ "$COVERAGE" = true ]; then
+        echo "Running tests with coverage..."
+        if ! npx vitest run --coverage; then
+            echo "ERROR: Tests failed"
+            exit 1
+        fi
+        echo "Tests passed with coverage!"
+    else
+        echo "Running tests..."
+        if ! npx vitest run; then
+            echo "ERROR: Tests failed"
+            exit 1
+        fi
+        echo "Tests passed!"
+    fi
+else
+    echo "=== Tests (related to ${#RELEVANT_FILES[@]} changed files) ==="
+
+    if [ "$WATCH" = true ]; then
+        echo "Running related tests in watch mode..."
+        npx vitest --related "${RELEVANT_FILES[@]}"
+    elif [ "$COVERAGE" = true ]; then
+        echo "Running related tests with coverage..."
+        if ! npx vitest run --related "${RELEVANT_FILES[@]}" --coverage; then
+            echo "ERROR: Tests failed"
+            exit 1
+        fi
+        echo "Tests passed with coverage!"
+    else
+        echo "Running related tests..."
+        if ! npx vitest run --related "${RELEVANT_FILES[@]}"; then
+            echo "ERROR: Tests failed"
+            exit 1
+        fi
+        echo "Tests passed!"
+    fi
+fi
+
+exit 0
diff --git a/javascript/check_vitest_all.sh b/javascript/check_vitest_all.sh
new file mode 100755
index 0000000..65dde57
--- /dev/null
+++ b/javascript/check_vitest_all.sh
@@ -0,0 +1,23 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs the full vitest test suite.
+# No file arguments required — runs `npx vitest run`.
+# Exits 1 if tests fail, 0 on success.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+
+cd "$PROJECT_ROOT"
+
+echo "Running tests..."
+if ! npx vitest run; then
+    echo "ERROR: Tests failed"
+    exit 1
+fi
+
+echo "Tests passed!"
+
+exit 0
diff --git a/tests/javascript/eslint_all/cases/01_eslint_passes.sh b/tests/javascript/eslint_all/cases/01_eslint_passes.sh
new file mode 100755
index 0000000..dc19e08
--- /dev/null
+++ b/tests/javascript/eslint_all/cases/01_eslint_passes.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Test: ESLint passes when npx exits 0
+# Expected: exit 0, message about issues fixed
+# ------------------------------------------------------------------------------
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/../../../lib/test_helper.bash"
+
+setup_test_env "eslint_all_passes"
+
+mock_npx 0 "All good"
+
+run_hook_at_depth "javascript/check_eslint_all.sh" 2
+
+assert_exit_code 0
+assert_output_contains "ESLint issues fixed"
+
+test_passed
diff --git a/tests/javascript/eslint_all/cases/02_eslint_fails.sh b/tests/javascript/eslint_all/cases/02_eslint_fails.sh
new file mode 100755
index 0000000..a8f0594
--- /dev/null
+++ b/tests/javascript/eslint_all/cases/02_eslint_fails.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Test: ESLint fails when npx exits 1
+# Expected: exit 1, error message
+# ------------------------------------------------------------------------------
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/../../../lib/test_helper.bash"
+
+setup_test_env "eslint_all_fails"
+
+mock_npx 1 "Lint errors found"
+
+run_hook_at_depth "javascript/check_eslint_all.sh" 2
+
+assert_exit_code 1
+assert_output_contains "ERROR"
+
+test_passed
diff --git a/tests/javascript/eslint_all/run.sh b/tests/javascript/eslint_all/run.sh
new file mode 100755
index 0000000..6b2341b
--- /dev/null
+++ b/tests/javascript/eslint_all/run.sh
@@ -0,0 +1,26 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs all check_eslint_all hook test cases.
+# Executes each case script in the cases/ directory.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+PASSED=0
+FAILED=0
+
+for case_file in "$SCRIPT_DIR"/cases/*.sh; do
+    [[ -f "$case_file" ]] || continue
+
+    if "$case_file"; then
+        ((PASSED++)) || true
+    else
+        ((FAILED++)) || true
+    fi
+done
+
+echo ""
+echo "ESLint all tests: $PASSED passed, $FAILED failed"
+
+[[ $FAILED -eq 0 ]]
diff --git a/tests/javascript/tests_exist/cases/01_no_files_exits_zero.sh b/tests/javascript/tests_exist/cases/01_no_files_exits_zero.sh
new file mode 100755
index 0000000..5341c90
--- /dev/null
+++ b/tests/javascript/tests_exist/cases/01_no_files_exits_zero.sh
@@ -0,0 +1,18 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Test: No files provided and no staged files exits with 0
+# Expected: exit 0, message about no staged TypeScript files
+# ------------------------------------------------------------------------------
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/../../../lib/test_helper.bash"
+
+setup_test_env "tests_exist_no_files"
+
+run_hook_at_depth "javascript/check_tests_exist.sh" 2
+
+assert_exit_code 0
+assert_output_contains "No staged TypeScript files"
+
+test_passed
diff --git a/tests/javascript/tests_exist/cases/02_non_ts_files_ignored.sh b/tests/javascript/tests_exist/cases/02_non_ts_files_ignored.sh
new file mode 100755
index 0000000..19d286b
--- /dev/null
+++ b/tests/javascript/tests_exist/cases/02_non_ts_files_ignored.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Test: Non-TypeScript files are ignored
+# Expected: exit 0, message about no staged TypeScript files
+# ------------------------------------------------------------------------------
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/../../../lib/test_helper.bash"
+
+setup_test_env "tests_exist_non_ts_ignored"
+
+create_fixture "app/utils.js" "export const foo = 1;"
+
+run_hook_at_depth "javascript/check_tests_exist.sh" 2 "app/utils.js"
+
+assert_exit_code 0
+assert_output_contains "All files have tests"
+
+test_passed
diff --git a/tests/javascript/tests_exist/cases/03_file_with_test_passes.sh b/tests/javascript/tests_exist/cases/03_file_with_test_passes.sh
new file mode 100755
index 0000000..20befed
--- /dev/null
+++ b/tests/javascript/tests_exist/cases/03_file_with_test_passes.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Test: TypeScript file with matching test file passes
+# Expected: exit 0, message about all files having tests
+# ------------------------------------------------------------------------------
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/../../../lib/test_helper.bash"
+
+setup_test_env "tests_exist_file_with_test"
+
+create_fixture "app/utils.ts" "export const foo = 1;"
+create_fixture "tests/app/utils.test.ts" "test('foo', () => {});"
+
+run_hook_at_depth "javascript/check_tests_exist.sh" 2 "app/utils.ts"
+
+assert_exit_code 0
+assert_output_contains "All files have tests"
+
+test_passed
diff --git a/tests/javascript/tests_exist/cases/04_file_missing_test_fails.sh b/tests/javascript/tests_exist/cases/04_file_missing_test_fails.sh
new file mode 100755
index 0000000..4bc642a
--- /dev/null
+++ b/tests/javascript/tests_exist/cases/04_file_missing_test_fails.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Test: TypeScript file without matching test file fails
+# Expected: exit 1, message about missing tests
+# ------------------------------------------------------------------------------
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/../../../lib/test_helper.bash"
+
+setup_test_env "tests_exist_missing_test"
+
+create_fixture "app/utils.ts" "export const foo = 1;"
+
+run_hook_at_depth "javascript/check_tests_exist.sh" 2 "app/utils.ts"
+
+assert_exit_code 1
+assert_output_contains "Missing tests"
+
+test_passed
diff --git a/tests/javascript/tests_exist/cases/05_skip_patterns_work.sh b/tests/javascript/tests_exist/cases/05_skip_patterns_work.sh
new file mode 100755
index 0000000..639cce1
--- /dev/null
+++ b/tests/javascript/tests_exist/cases/05_skip_patterns_work.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Test: Files matching skip patterns are skipped
+# Expected: exit 0, file listed as skipped
+# ------------------------------------------------------------------------------
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/../../../lib/test_helper.bash"
+
+setup_test_env "tests_exist_skip_patterns"
+
+create_fixture "app/next.config.ts" "export default {};"
+
+run_hook_at_depth "javascript/check_tests_exist.sh" 2 "app/next.config.ts"
+
+assert_exit_code 0
+assert_output_contains "Skipped"
+
+test_passed
diff --git a/tests/javascript/tests_exist/run.sh b/tests/javascript/tests_exist/run.sh
new file mode 100755
index 0000000..4291fd1
--- /dev/null
+++ b/tests/javascript/tests_exist/run.sh
@@ -0,0 +1,26 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs all check_tests_exist hook test cases.
+# Executes each case script in the cases/ directory.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+PASSED=0
+FAILED=0
+
+for case_file in "$SCRIPT_DIR"/cases/*.sh; do
+    [[ -f "$case_file" ]] || continue
+
+    if "$case_file"; then
+        ((PASSED++)) || true
+    else
+        ((FAILED++)) || true
+    fi
+done
+
+echo ""
+echo "Tests exist tests: $PASSED passed, $FAILED failed"
+
+[[ $FAILED -eq 0 ]]
diff --git a/tests/javascript/vitest/cases/01_no_files_runs_full_suite.sh b/tests/javascript/vitest/cases/01_no_files_runs_full_suite.sh
new file mode 100755
index 0000000..e52b076
--- /dev/null
+++ b/tests/javascript/vitest/cases/01_no_files_runs_full_suite.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Test: No files runs full test suite
+# Expected: exit 0, message about full suite
+# ------------------------------------------------------------------------------
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/../../../lib/test_helper.bash"
+
+setup_test_env "vitest_no_files_full_suite"
+
+mock_npx 0 "Tests passed"
+
+run_hook_at_depth "javascript/check_vitest.sh" 2
+
+assert_exit_code 0
+assert_output_contains "full suite"
+
+test_passed
diff --git a/tests/javascript/vitest/cases/02_ts_files_runs_related.sh b/tests/javascript/vitest/cases/02_ts_files_runs_related.sh
new file mode 100755
index 0000000..9f05f56
--- /dev/null
+++ b/tests/javascript/vitest/cases/02_ts_files_runs_related.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Test: Passing .ts files runs related tests
+# Expected: exit 0, message about related files
+# ------------------------------------------------------------------------------
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/../../../lib/test_helper.bash"
+
+setup_test_env "vitest_ts_files_related"
+
+mock_npx 0 "Tests passed"
+
+create_fixture "app/utils.ts" "export const foo = 1;"
+
+run_hook_at_depth "javascript/check_vitest.sh" 2 "app/utils.ts"
+
+assert_exit_code 0
+assert_output_contains "related"
+
+test_passed
diff --git a/tests/javascript/vitest/cases/03_test_failure_exits_one.sh b/tests/javascript/vitest/cases/03_test_failure_exits_one.sh
new file mode 100755
index 0000000..4260355
--- /dev/null
+++ b/tests/javascript/vitest/cases/03_test_failure_exits_one.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Test: Test failure exits with 1
+# Expected: exit 1, error message
+# ------------------------------------------------------------------------------
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck disable=SC1091
+source "$SCRIPT_DIR/../../../lib/test_helper.bash"
+
+setup_test_env "vitest_failure_exits_one"
+
+mock_npx 1 "Test failed"
+
+run_hook_at_depth "javascript/check_vitest.sh" 2
+
+assert_exit_code 1
+assert_output_contains "ERROR"
+
+test_passed
diff --git a/tests/javascript/vitest/run.sh b/tests/javascript/vitest/run.sh
new file mode 100755
index 0000000..35f27c5
--- /dev/null
+++ b/tests/javascript/vitest/run.sh
@@ -0,0 +1,26 @@
+#!/bin/bash
+# ------------------------------------------------------------------------------
+# Runs all check_vitest hook test cases.
+# Executes each case script in the cases/ directory.
+# ------------------------------------------------------------------------------
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+PASSED=0
+FAILED=0
+
+for case_file in "$SCRIPT_DIR"/cases/*.sh; do
+    [[ -f "$case_file" ]] || continue
+
+    if "$case_file"; then
+        ((PASSED++)) || true
+    else
+        ((FAILED++)) || true
+    fi
+done
+
+echo ""
+echo "Vitest tests: $PASSED passed, $FAILED failed"
+
+[[ $FAILED -eq 0 ]]
diff --git a/tests/lib/test_helper.bash b/tests/lib/test_helper.bash
index 0809022..95d78da 100755
--- a/tests/lib/test_helper.bash
+++ b/tests/lib/test_helper.bash
@@ -212,6 +212,20 @@ mock_git_branch() {
     git -C "$TEST_DIR" checkout -q "$branch_name" 2>/dev/null || true
 }
 
+mock_npx() {
+    local exit_code="$1"
+    local output="${2:-}"
+
+    mkdir -p "$TEST_DIR/bin"
+    cat > "$TEST_DIR/bin/npx" << EOF
+#!/bin/bash
+echo "$output"
+exit $exit_code
+EOF
+    chmod +x "$TEST_DIR/bin/npx"
+    export PATH="$TEST_DIR/bin:$PATH"
+}
+
 mock_docker_compose() {
     mkdir -p "$TEST_DIR/bin"
     cat > "$TEST_DIR/bin/docker" << 'EOF'
@@ -255,6 +269,40 @@ run_hook() {
     set -e
 }
 
+run_hook_at_depth() {
+    local hook_path="$1"
+    local depth="$2"
+    shift 2
+    local args=("$@")
+
+    # Get absolute path to hook
+    local script_dir
+    script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+    local full_hook_path="$script_dir/$hook_path"
+
+    if [[ ! -f "$full_hook_path" ]]; then
+        echo -e "${RED}[ERROR]${NC} Hook not found: $full_hook_path"
+        return 1
+    fi
+
+    # Build nested directory path inside TEST_DIR
+    local nested_dir="$TEST_DIR"
+    for ((i = 0; i < depth; i++)); do
+        nested_dir="$nested_dir/level_$i"
+    done
+    mkdir -p "$nested_dir"
+
+    # Copy hook script into nested directory
+    cp "$full_hook_path" "$nested_dir/hook.sh"
+    chmod +x "$nested_dir/hook.sh"
+
+    # Run hook and capture output
+    set +e
+    LAST_OUTPUT=$("$nested_dir/hook.sh" "${args[@]}" 2>&1)
+    LAST_EXIT_CODE=$?
+    set -e
+}
+
 # -----------------------------------------
 # Assertions
 # -----------------------------------------