fix(dev): avoid polynomial regex backtracking in toCamelCase helper (#5148)

* fix(dev): avoid polynomial regex backtracking in toCamelCase helper

* Add test for toCamelCase with non-word character separators

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

tools/build-helpers/package.json

@@ -5,6 +5,9 @@
   "description": "A internal used package with helpers.",
   "main": "helpers.ts",
   "types": "helpers.ts",
+  "scripts": {
+    "test": "vitest run"
+  },
   "author": "",
   "license": "ISC",
   "type": "module",

tools/build-helpers/src/toCamelCase.spec.ts

@@ -0,0 +1,42 @@
+import { describe, expect, it } from 'vitest';
+import { toCamelCase } from './toCamelCase.ts';
+
+describe('toCamelCase', () => {
+  it('converts kebab-case icon names', () => {
+    expect(toCamelCase('arrow-up')).toBe('arrowUp');
+    expect(toCamelCase('circle-arrow-out-down-left')).toBe('circleArrowOutDownLeft');
+    expect(toCamelCase('arrow-up-0-1')).toBe('arrowUp01');
+  });
+
+  it('treats whitespace, hyphens and underscores as separators', () => {
+    expect(toCamelCase('foo_bar')).toBe('fooBar');
+    expect(toCamelCase('foo bar')).toBe('fooBar');
+    expect(toCamelCase('foo\tbar')).toBe('fooBar');
+    expect(toCamelCase('foo - _\tbar')).toBe('fooBar');
+    expect(toCamelCase('-foo')).toBe('Foo');
+  });
+
+  it('lowercases only a leading capital letter', () => {
+    expect(toCamelCase('Foo-bar')).toBe('fooBar');
+    expect(toCamelCase('FooBar')).toBe('fooBar');
+    expect(toCamelCase('alreadyCamelCase')).toBe('alreadyCamelCase');
+  });
+
+  it('keeps separators that are not followed by a word character', () => {
+    expect(toCamelCase('foo-')).toBe('foo-');
+    expect(toCamelCase('foo__')).toBe('foo__');
+    expect(toCamelCase('foo\t!')).toBe('foo\t!');
+    expect(toCamelCase('')).toBe('');
+  });
+
+  it('handles long runs of tabs in linear time', () => {
+    const input = `a${'\t'.repeat(100_000)}!`;
+
+    const start = performance.now();
+    const result = toCamelCase(input);
+    const duration = performance.now() - start;
+
+    expect(result).toBe(input);
+    expect(duration).toBeLessThan(100);
+  });
+});

tools/build-helpers/src/toCamelCase.ts

@@ -5,6 +5,6 @@
  * @returns {string} A camelized string
  */
 export const toCamelCase = (string: string): string =>
-  string.replace(/^([A-Z])|[\s-_]+(\w)/g, (match, p1, p2) =>
-    p2 ? p2.toUpperCase() : p1.toLowerCase(),
+  string.replace(/^([A-Z])|[\s-_]+(\w)?/g, (match, p1, p2) =>
+    p1 ? p1.toLowerCase() : p2 ? p2.toUpperCase() : match,
   );