What is the use case for var in ES6?

Question

If the let keyword introduces a proper implementation of block scope, does var any longer have a use case? I am looking at this from a software des

Answer 1

You can use var if you want to deconstruct something into the function scope, for example a conditional:

if (Math.random() > 0.5)
  var {a,b} = {a: 1, b: 2}
else 
  var {a,b} = {a: 10, b: 20}

// Some common logic on a and b
console.log(a, b)

With let you would have to write something like

let result;

if (Math.random() > 0.5)
  result = {a: 'foo', b: 'bar'}
else 
  result = {a: 'baz', b: 'qux'}

// Using const might make more sense here
let {a, b} = result; 
// Some common logic on a and b
console.log(a,b)