As far as I know, not using var will put any declaration in the global scope. So while you wouldn't want to do that on a real production app. Using it for these little solutions isn't necessarily wrong. As you probably don't need to worry about your namespace

here's an example:
drink = 'beer'
function drunk () {
console.log(drink)
}
drunk()
//'beer'
function wino () {
var drink = 'wine';
console.log(drink)
}
wino()
// 'wine'
drink
// 'beer'

Tests don't account for edge cases