From 96e34fbb7d7bb556392646a7a6720182953ac275 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Tue, 21 Mar 2023 11:37:46 +0100
Subject: [PATCH] Enable the `unicorn/prefer-negative-index` ESLint plugin rule

Please see https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/prefer-negative-index.md
---
 .eslintrc                  | 1 +
 src/core/core_utils.js     | 4 ++--
 src/core/type1_parser.js   | 2 +-
 src/core/xfa/utils.js      | 2 +-
 src/core/xfa/xfa_object.js | 4 ++--
 5 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/.eslintrc b/.eslintrc
index 5418053e4..69e14e7c8 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -59,6 +59,7 @@
     "unicorn/prefer-dom-node-remove": "error",
     "unicorn/prefer-logical-operator-over-ternary": "error",
     "unicorn/prefer-modern-dom-apis": "error",
+    "unicorn/prefer-negative-index": "error",
     "unicorn/prefer-regexp-test": "error",
     "unicorn/prefer-string-replace-all": "error",
     "unicorn/prefer-string-starts-ends-with": "error",
diff --git a/src/core/core_utils.js b/src/core/core_utils.js
index 3e6f64adf..fd16b2373 100644
--- a/src/core/core_utils.js
+++ b/src/core/core_utils.js
@@ -471,12 +471,12 @@ function validateCSSFont(cssFontInfo) {
 
   // See https://developer.mozilla.org/en-US/docs/Web/CSS/string.
   if (/^".*"$/.test(fontFamily)) {
-    if (/[^\\]"/.test(fontFamily.slice(1, fontFamily.length - 1))) {
+    if (/[^\\]"/.test(fontFamily.slice(1, -1))) {
       warn(`XFA - FontFamily contains some unescaped ": ${fontFamily}.`);
       return false;
     }
   } else if (/^'.*'$/.test(fontFamily)) {
-    if (/[^\\]'/.test(fontFamily.slice(1, fontFamily.length - 1))) {
+    if (/[^\\]'/.test(fontFamily.slice(1, -1))) {
       warn(`XFA - FontFamily contains some unescaped ': ${fontFamily}.`);
       return false;
     }
diff --git a/src/core/type1_parser.js b/src/core/type1_parser.js
index ca5c78bba..13d04396f 100644
--- a/src/core/type1_parser.js
+++ b/src/core/type1_parser.js
@@ -265,7 +265,7 @@ class Type1CharString {
             subrNumber = this.stack.pop();
             const numArgs = this.stack.pop();
             if (subrNumber === 0 && numArgs === 3) {
-              const flexArgs = this.stack.splice(this.stack.length - 17, 17);
+              const flexArgs = this.stack.splice(-17, 17);
               this.stack.push(
                 flexArgs[2] + flexArgs[0], // bcp1x + rpx
                 flexArgs[3] + flexArgs[1], // bcp1y + rpy
diff --git a/src/core/xfa/utils.js b/src/core/xfa/utils.js
index 5d5cf4cc7..5f93bd458 100644
--- a/src/core/xfa/utils.js
+++ b/src/core/xfa/utils.js
@@ -26,7 +26,7 @@ const measurementPattern = /([+-]?\d+\.?\d*)(.*)/;
 
 function stripQuotes(str) {
   if (str.startsWith("'") || str.startsWith('"')) {
-    return str.slice(1, str.length - 1);
+    return str.slice(1, -1);
   }
   return str;
 }
diff --git a/src/core/xfa/xfa_object.js b/src/core/xfa/xfa_object.js
index 30f6cfd2a..ee49d2b3c 100644
--- a/src/core/xfa/xfa_object.js
+++ b/src/core/xfa/xfa_object.js
@@ -481,9 +481,9 @@ class XFAObject {
       // - URI
       // For now we don't handle URI other than "." (current document).
       if (usehref.startsWith("#som(") && usehref.endsWith(")")) {
-        somExpression = usehref.slice("#som(".length, usehref.length - 1);
+        somExpression = usehref.slice("#som(".length, -1);
       } else if (usehref.startsWith(".#som(") && usehref.endsWith(")")) {
-        somExpression = usehref.slice(".#som(".length, usehref.length - 1);
+        somExpression = usehref.slice(".#som(".length, -1);
       } else if (usehref.startsWith("#")) {
         id = usehref.slice(1);
       } else if (usehref.startsWith(".#")) {