ternary.md

if is not an expression, meaning it does not return a value. A ternary is an expression, meaning it does return a value. This allows you to use it on the right hand side of an assignment operator.

So when assigning things, this is needlessly verbose

var someEl = document.getElementById('some-element');
if (isCool) {
  someEl.innerText = 'totally cool';
} else {
  someEl.innerText = 'NOT COOL YO';
}

when you could have just:

var someEl = document.getElementById('some-element');
someEl.innerText = isCool ? 'totally cool' : 'NOT COOL YO';

Like any programming construct, you can use it badly. A common mistake is putting complex logic in that bitch:

var foo = obj.foo && obj.bar.baz === 'whatever' || obj.wtf > obj.bbq ? 'herp' : 'derp'

And if you start nesting them, I kill you:

// Syntactically valid but FUCK YOU
var foo = isBar ? isFoo ? 'A' : 'B' : barType == 'iron' ? 'C' : 'D'

TL:DR; the ternary is nice when your condition and your branches are simple, and you want a return value from it. But it's easy to abuse, and if your logic gets more complex refactor your code and change that to a proper multiline if statement for better readability. But when used wisely, they can enhance readability by keeping code more concise.