SyntaxError which says “Cannot use the keyword ‘delete’ as a variable name”.
But it’s perfectly fine to use ES6 reserved words like
let as a variable name in ES5.
One might wonder how this code should work in ES6 runtime since
let is a reserved work and can not be used as a variable name.
Even when using ES6 new features like arrow functions or spreading it’s legal to use FutureReservedWords as variable names: