nullnundefined6.js

var foo = null;

if (foo > 9) {
    console.log('greater than 9');
}
if (foo < 9) {
    console.log('less than 9');
}

if (foo > -9) {
    console.log('greater than -9');
}
if (foo < -9) {
    console.log('less than -9');
}
if (foo == 0) {
    console.log('equal to zero');
}
if (foo === 0) {
    console.log('equal to zero');
}