Jul 8, 2025 · The const declaration declares block-scoped local variables. The value of a constant can't be changed through reassignment using the assignment operator, but if a constant is an object, its …

Constant Objects and Arrays The keyword const is a little misleading. It does not define a constant value. It defines a constant reference to a value. Because of this you can NOT: Reassign a constant …

Block Scope Before ES6 (2015), JavaScript did not have Block Scope. JavaScript had Global Scope and Function Scope. ES6 introduced the two new JavaScript keywords: let and const. These two …

Feb 24, 2026 · JavaScript arrays are zero-indexed: the first element of an array is at index 0, the second is at index 1, and so on — and the last element is at the value of the array's length property minus 1. …

Oct 3, 2025 · In JavaScript, an array is an ordered list of values. Each value, known as an element, is assigned a numeric position in the array called its index. The indexing starts at 0, so the first element …

Jul 8, 2025 · The let declaration declares re-assignable, block-scoped local variables, optionally initializing each to a value.

Apr 2, 2020 · var declarations are globally scoped or function scoped while let and const are block scoped. var variables can be updated and re-declared within its scope; let variables can be updated …

Jan 16, 2026 · JavaScript provides three ways to declare variables: var, let, and const, but they differ in scope, hoisting behaviour, and re-assignment rules. var: Declares variables with function or global …

Nov 20, 2025 · Arrays in JavaScript can work both as a queue and as a stack. They allow you to add/remove elements, both to/from the beginning or the end. In computer science, the data structure …

Apr 18, 2009 · ES6 introduced JavaScript developers the let and const keywords. While let and const are block-scoped and not function scoped as var it shouldn’t make a difference while discussing their …