Скачать или смотреть JavaScript Function Declaration vs Expression

T**differences between two primary ways of declaring functions in JavaScript**: function declarations (e.g., `function functionName() {}`) and function expressions (e.g., `var functionName = function() {}`). A key distinction lies in *hoisting**, where function declarations are fully moved to the top of their scope during parsing, making them accessible before their physical definition, while only the variable declaration for function expressions is hoisted, leading to an `undefined` state until the assignment line is reached during runtime. The discussion also covers **scoping behavior* (especially in strict mode and ES2015+ with block scope), **function naming for debugging**, **performance considerations**, and **mutability**, providing examples and historical context for each method and other function creation syntaxes like arrow functions and class methods. Ultimately, while both methods achieve similar results in many cases, their underlying mechanics and implications for code structure, debugging, and execution timing differ significantly.