What's the difference between `null` and `undefined` in JavaScript? What will be logged to the console? (think well, then click for the answer and explanation)
In the first line, we evaluate null === null
and the result is true
.
In the second line, we evaluate undefined === undefined
and the result is true
once again.
In the third line, however, we need to understand what the result of null + undefined
is. For JavaScript, it’s hard to make sense of what it should be, so it evaluates this expression as NaN
.
Now, is NaN
equal to NaN
?
And the answer is - NO.
In JS NaN
is the only value that’s not equal to itself.
ANSWER: The output is going to be true
, true
, and false
.