Vega Expression Parser and Code Generator

vega-expression is a JavaScript/TypeScript library that provides a secure and configurable expression parser and code generator, forming a core component of the broader Vega visualization toolkit. It processes a limited subset of JavaScript expressions into an Abstract Syntax Tree (AST) and then generates `eval`'able JavaScript code. The library intentionally restricts language features like assignment operators, `new` expressions, and control flow to prioritize security and prevent unwanted side effects, making it suitable for user-provided expressions in visualization contexts. It is currently in active development, with version 6.2.0 as the latest stable release at the time of this entry, following a fairly active release cadence that often aligns with the larger Vega monorepo. Its key differentiators include its security-first approach, a stripped-down Esprima-based parser, and highly configurable code generation options for managing constants, functions, and variable scopes, including tracking data field dependencies.