What do the curly braces do in switch statement after case in es6?

Question

What\'s the difference between:

switch (expression) {
    case:
      somethings;
      break;
}

and

switch (expression) {
         


        

Answer 1

you have to use curly brackets:

1. when creating more block scoped variables (const / let) with the same name
   • according to spec MDN web docs
   • ERROR: Uncaught SyntaxError: Identifier 'variablename' has already been declared
2. when using eslint in default settings and using even single one (const / let)
   • according to rule no-case-declarations
   • ERROR: Unexpected lexical declaration in case block no-case-declarations