Here, instead of passing the variable as the whole string, you could've given just your name and console.log the string after, like:

const hacker1 = 'Leal';
 console.log(`The driver's name is ${hacker1}.`);
 const hacker2 = 'Duarte';
 console.log(`The navigator's name is ${hacker2}.`)

So here you wouldn't need to use slice();

Great job on creating the variables numOfCharDriver and numOfCharNavigator . Here on the if statement, you could've used them like:

if( numOfCharDriver > numOfCharNavigator)

Here, the idea was to print all the characters of the driver's name, separated by a space and in capitals i.e. "L E A L".

A good solution would be:

let withSpace = '';
for (let i = 0; i < hacker1.length; i++) {
     withSpace += hacker1.[i] + ' ';
 }
console.log(withSpace.toUpperCase());

Here, the idea was to print all the characters of the navigator's name in reverse order. i.e. "etrauD"

One way of doing that:

let reverseName = '';
for (let i = hacker2.length - 1; i >= 0; i--) {
  reverseName += hacker2[i];
}
console.log(reverseName);