Normally by pressing F12 or using inspect on your result pane.
Alternatively
for (var i = 0; i < 5; i++) {
console.log(i); // 0, 1, 2, 3, 4
}
console.log({
foo: 'bar',
baz: function() {}
});
console.log([1, 2, 3]);
console.log(window.alert);
throw new Error('This is error log..');
<script src="https://cdn.jsdelivr.net/gh/eu81273/jsfiddle-console/console.js"></script>