Comprehensive guide for implementing robust testing strategies in JavaScript/TypeScript applications using modern testing frameworks and best practices. Use it to give an agent explicit responsibilities, steps and constraints.

1. Basic Syntax 2. Operators Arithmetic Comparison Logical Other 3. Declarations 4. Functions Functions as values and closures Variadic Functions 5. Built-in Types 6. Type Conversions 7. Packages 8. Control structures If Loops Switch 9. Arrays, Slices, Ranges. Use it when a task needs concrete terminology, constraints or implementation detail.