Interview Q&A / JavaScript

1. What is the difference between var, let and const? Explain hoisting and the temporal dead zone.

   var is function-scoped and is hoisted with the value undefined. let and const are block-scoped and are hoisted too, but cannot be used before their declaration line; that gap is the temporal dead zone. const also cannot be reassigned, though an object it holds can still be changed.

   BeginnerIn-depth3 min read
2. What is the difference between a function declaration and a function expression?

   A declaration is hoisted with its body, so you can call it before the line it appears on. An expression assigns a function to a variable, and the variable follows var, let or const rules, so calling it early fails.

   BeginnerQuick answer1 min read