Block statement

block.statement.js

for(var i = 1; i <= 5; i++) {
  console.log('Number: ' + i);
}

// Variable i is accessible here
console.log(i) // -> 6 - which is the last value of i incremented by 1

/**
 * However, using the ES6 let or const keyword to declare the variable
 * makes it behave like a scope as it's only accessible within the for 
 * loop block.
 */
for(let x = 1; x <= 5; x++) {
  console.log('Number: ' + x);
}

// Access variable j outside the block throws
console.log(x) // -> ReferenceError: x is not defined