One-line short-circuit evaluation with && || in JavaScript

Question

var prefix = options && options.prefix || '';

In JavaScipt in my case. Can someone explain what kind of statement or condition is this? Or at the end what's the value of prefix variable?

I know about (ternary operator):

condition ? expr1 : expr2

but this was different.

Answer 1

This one-liner is the equivalent of saying:

var prefix;
if(options && options.prefix){
  prefix = options.prefix;
} else{
  prefix = '';
}