AST Transformation with Safe Cloning

Build a JavaScript code transformation utility that safely transforms code while preserving the original Abstract Syntax Tree (AST) for comparison purposes.

Requirements

Create a module that exports a function transformWithComparison that:

1. Accepts JavaScript source code as a string
2. Transforms all var declarations to const declarations
3. Returns an object containing:
   • original: The original, unmodified AST (must remain unchanged even after transformation)
   • transformed: The transformed JavaScript code as a string
   • wasModified: A boolean indicating whether any var-to-const transformations occurred

The original AST must remain completely unmodified after the transformation completes, preserving its initial state for comparison purposes.

@generates

API

/**
 * Transforms JavaScript code while preserving the original AST.
 *
 * @param {string} sourceCode - The JavaScript source code to transform
 * @returns {Object} An object with original AST, transformed code, and modification status
 * @returns {Object} returns.original - The original, unmodified AST
 * @returns {string} returns.transformed - The transformed JavaScript code
 * @returns {boolean} returns.wasModified - Whether any transformations were applied
 */
function transformWithComparison(sourceCode) {
  // Implementation
}

module.exports = { transformWithComparison };

Test Cases

• Given code var x = 1;, the function returns an object where transformed is const x = 1;, wasModified is true, and original is an unmodified AST @test
• Given code const y = 2; (already using const), the function returns wasModified as false and transformed equals the input @test
• After transformation, the original AST's VariableDeclaration nodes still have kind "var" (not mutated) @test

Dependencies { .dependencies }

@babel/core { .dependency }

Provides JavaScript transformation and parsing capabilities with AST cloning support.

@satisfied-by