Add comprehensive ES6+ support and modernization

[coderabbitai]

Goal

Modernize the Allonsh.js codebase to fully embrace ES6+ JavaScript features for better developer experience, performance, and maintainability.

Current State Analysis

The codebase currently uses a mix of traditional and modern JavaScript patterns. This issue aims to standardize on modern ES6+ features throughout.

ES6+ Features to Implement

1. Arrow Functions

• Replace traditional function expressions with arrow functions where appropriate
• Maintain proper this binding context

2. Template Literals

• Replace string concatenation with template literals for better readability
• Especially useful for CSS selectors, error messages, and logging

3. Destructuring Assignment

• Extract values from options objects more elegantly
• Simplify parameter handling in methods

4. Enhanced Object Literals

• Use shorthand property names and methods
• Computed property names where beneficial

5. Default Parameters

• Replace manual undefined checks with default parameters
• Cleaner constructor and method signatures

6. Const/Let Usage

• Audit all var declarations and convert to const/let
• Follow block scoping best practices

7. Spread/Rest Operators

• Use spread syntax for object merging
• Rest parameters for flexible function arguments

8. Enhanced Array Methods

• Utilize find(), includes(), some(), every() where appropriate
• Replace traditional loops with functional array methods

Files to Update

• src/allonsh.js (primary target)
• demo/js/script.js (demo modernization)
• test/allonsh.test.js (test code modernization)

Benefits

• More readable and maintainable code
• Better performance in modern JavaScript engines
• Improved developer experience
• Alignment with current JavaScript best practices
• Smaller bundle sizes with modern tooling

Browser Support Considerations

• ES6 has excellent browser support (95%+ global coverage)
• Target: Chrome 51+, Firefox 54+, Safari 10+, Edge 79+
• Transpilation can be added later for legacy browser support if needed

Acceptance Criteria

• All var declarations converted to const/let
• Arrow functions used where appropriate (maintaining correct this context)
• Template literals replace string concatenation
• Destructuring used for object/array operations
• Default parameters replace manual undefined checks
• Modern array methods utilized throughout
• Code passes existing tests with no functionality changes
• Documentation updated with modern syntax examples

Priority

Medium - Code quality improvement that enhances maintainability

Estimated Effort

2-3 days for comprehensive modernization across all files