What are the ways to declare variables in JavaScript? Name the differences between these methods.

In JavaScript, variables can be declared in three ways: var, let, const.

Differences between them:

Difference	var	let	const
Scope	Function scope	Block scope	Block scope
Redeclaration	Possible	Possible	Not possible
Reassignment	Possible	Possible	Not possible
Hoisting	Hoists declaration and initialization to undefined	Hoists declaration but not initialization	Hoists declaration but not initialization

Examples:

// var
function exampleVar() {
  var x = 10; // Function scope
  if (true) {
    var x = 20; // Redeclaration possible within the same function
    console.log(x); // 20
  }
  console.log(x); // 20 (the x from if is accessible here)
}

console.log(x); // Error: ReferenceError: x is not defined (x is not visible outside the function)

// Hoisting var
console.log(a); // undefined
var a = 5;
console.log(a); // 5

// let
function exampleLet() {
  let y = 10; // Block scope
  if (true) {
    let y = 20; // Cannot redeclare within the same block
    console.log(y); // 20 (different y variable)
  }
  console.log(y); // 10 (y outside the block)
}

console.log(y); // Error: ReferenceError: y is not defined

// Hoisting let
// console.log(b); // Error: ReferenceError: Cannot access 'b' before initialization
let b = 5;
console.log(b); // 5

// const
function exampleConst() {
  const z = 10; // Block scope
  // z = 20; // Error: TypeError: Assignment to constant variable. (Reassignment not allowed)
  if (true) {
    const z = 20; // Cannot redeclare within the same block
    console.log(z); // 20 (different z variable)
  }
  console.log(z); // 10 (z outside the block)
}

console.log(z); // Error: ReferenceError: z is not defined

// Hoisting const
// console.log(c); // Error: ReferenceError: Cannot access 'c' before initialization
const c = 5;
console.log(c); // 5

// For objects and arrays declared with const, contents can be modified
const obj = { name: 'Test' };
obj.name = 'New Test'; // Allowed
// obj = { name: 'Another Test' }; // Error