Variable Hoisting
Variable hoisting is a JavaScript behavior where variable and function declarations are moved to the top of their containing scope during the compilation phase, before code execution. This means that variables declared with 'var' can be accessed before their actual declaration in the code, though they return 'undefined' until initialized. It's a fundamental concept for understanding JavaScript's execution context and scope chain.
Developers should learn variable hoisting to avoid bugs and write predictable JavaScript code, especially when dealing with 'var' declarations, as it explains why accessing variables before declaration doesn't throw errors but returns 'undefined'. It's crucial for debugging scope-related issues and understanding how JavaScript engines parse code, which is essential for working with legacy codebases or preparing for technical interviews that test core language knowledge.