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Breaking Changes

This document lists breaking changes between versions of @pro-fa/expr-eval.

Audience: Developers upgrading between versions

For detailed migration instructions, see the Migration Guide.

Version 6.0.0

Null Comparison Behavior

What Changed: Null comparisons now follow JavaScript semantics more closely. Previously, null == undefined returned true, but other null comparisons may have behaved unexpectedly.

Migration: Review expressions that compare values to null or undefined. Use the ?? (coalesce) operator for null/undefined fallback values.

Version 5.0.0

registerFunction Deprecated

What Changed: registerFunction() is deprecated. Use direct assignment to parser.functions instead.

Before: 

parser.registerFunction('double', (x) => x * 2);

After: 

parser.functions.double = (x) => x * 2;

Protected Properties

Access to the following properties is now blocked to prevent prototype pollution attacks: - __proto__ - prototype - constructor

Attempting to access these properties in variable names or member expressions will throw an AccessError.

Example: 

// These will throw AccessError
parser.evaluate('x.__proto__', { x: {} });
parser.evaluate('__proto__', { __proto__: {} });

Version 4.0.0

Concatenation Operator Changed from || to |

What Changed: The || operator was repurposed for logical OR (JavaScript-style). A new | (pipe) operator was introduced for array and string concatenation. Additionally, the && operator was added for logical AND.

Before (original expr-eval 2.x): 

// || was used for concatenation
parser.evaluate('"hello" || " world"');  // "hello world"
parser.evaluate('[1, 2] || [3, 4]');     // [1, 2, 3, 4]

After (v4.0.0+): 

// | is now used for concatenation
parser.evaluate('"hello" | " world"');   // "hello world"
parser.evaluate('[1, 2] | [3, 4]');      // [1, 2, 3, 4]

// || is now logical OR
parser.evaluate('true || false');        // true
parser.evaluate('false || true');        // true

// && is logical AND (new)
parser.evaluate('true && false');        // false
parser.evaluate('true && true');         // true

Migration Guide:

  1. Find concatenation usage: Search your expressions for || used with strings or arrays
  2. Replace with pipe: Change || to | for concatenation operations
  3. Review logical operations: If you were using or keyword, you can now also use ||

Package Renamed

The package was renamed from expr-eval to @pro-fa/expr-eval and ported to TypeScript.

# Remove old package
npm uninstall expr-eval

# Install new package
npm install @pro-fa/expr-eval

Update imports: 

// Before
const { Parser } = require('expr-eval');

// After
import { Parser } from '@pro-fa/expr-eval';