"..well Dim should be used not Local/Global, because JavaScript only has var"

[guinness]

Gotcha! Not anymore that let and const have been added to ES2015. So yeah, ES2015 is a step in the right direction.

function main() {
    let name = 'guiness';
    for (let i = 0; i < 10; i++) {
        let concat = name + i; // This is scoped only to the loop block
        console.log(concat);
    }
    // concat is not seen here, like it would if var was used.
}