I was coding in node, so I got an error, will you explain this error to me?
When I write a statement console.log(Email||Password||Song)
It's returning the value of Email variable.
console.log(!Email||!Password||!Song); So, first up the or (||) operator:
a || b === a if a is truthy, otherwise b
So the or operator isn't strictly useful for boolean types. For example, you could set a default value for data like
function makePerson(name, age) {
return { name: name, age: age || 0 }
}
Next, the not (!) operator:
!a === false if a is truthy, true otherwise
So note that the ! operator strictly provides boolean outputs.
So with your example,
Email||Password||Song
will be Email if truthy, then Password if truthy, and finally Song
!Email||!Password||!Song
is going to end up evaluating to something like
false||false||true
or
true||false||false
etc. By adding in the unary not, you're effectively casting all your inputs to booleans, and the output of the or operator is the type of its inputs.