How is TypeScript Compiler executing the code?

• TypeScript is a compiled language. It goes through a compilation process that converts TypeScript code into JavaScript code. The TypeScript compiler, called `tsc`, transforms TypeScript files (with the .ts extension) into equivalent JavaScript files (with the .js extension). This compilation step is necessary because browsers and JavaScript runtimes only understand and execute JavaScript code.

• During the compilation process, the TypeScript compiler performs various tasks, such as type checking, syntax validation, and transpiling TypeScript-specific syntax and features into JavaScript equivalents that are compatible with different versions of JavaScript.

• The TypeScript compiler, `tsc`, works by taking TypeScript code as input and performing a series of steps to generate equivalent JavaScript code that can be executed by a JavaScript runtime environment.

• Here's an overview of how the TypeScript compiler works:

• Lexical Analysis (Scanning): The TypeScript compiler scans the input TypeScript code to break it down into individual tokens (such as keywords, identifiers, operators, and literals). This process is known as lexical analysis or scanning.

• Syntax Analysis (Parsing): The compiler uses the tokens generated from the scanning phase to build an abstract syntax tree (AST). The AST represents the structure and relationships between different elements of the TypeScript code, such as variable declarations, function calls, and control flow statements. This step is known as syntax analysis or parsing.

• Semantic Analysis (Type Checking): TypeScript's key feature is its static type system. The compiler performs a semantic analysis of the AST to check for type errors, inconsistencies, and adherence to the type rules specified in the code. It verifies that variables are used correctly, function arguments match their expected types, and other type-related constraints are satisfied.

• Transpilation (Code Transformation): Once the type checking phase is complete and the code is determined to be valid, the compiler proceeds to transform the TypeScript code into equivalent JavaScript code. This process involves transpiling TypeScript-specific syntax, such as type annotations, interfaces, and decorators, into JavaScript equivalents or polyfills that achieve the desired behavior.

• Code Generation: Finally, the compiler generates JavaScript code based on the transformed AST. It emits JavaScript code that closely resembles the original TypeScript code, but without TypeScript-specific features and with any necessary transformations or translations applied. The resulting JavaScript code is saved to a file with the .js extension.

• After the TypeScript code is compiled into JavaScript, it can be executed by a JavaScript runtime environment, such as a web browser or Node.js, just like any other JavaScript code.

• It's important to note that the TypeScript compiler is highly configurable, and you can adjust its behavior through configuration files (such as `tsconfig.json`) to specify compiler options, target environments, and other settings that suit your project's requirements.

• The advantage of compilation in TypeScript is that it catches type-related errors and provides improved tooling support during development, helping developers write safer and more maintainable code.