Numerical transformation in javascript and math operation

Question

Here is the code:

alert(typeof(+"13t"));
alert(1 + (+"13t"));

Why in the first line the output is "number" And in the second line the output is "NaN"??

No offense, but we already had like million of questions about converting types in javascript and it always boils to RFTM. Just read MDN docs about it. — Tomáš Zato - Reinstate Monica, May 09 '16 at 14:07
What does `(+"13t")` return? :) That would answer your question. — epascarello, May 09 '16 at 14:08
Your perceived need for a quick answer isn't at all relevant here. Perform basic research. — , May 09 '16 at 14:17

score 6 · Accepted Answer · answered May 09 '16 at 14:06

6

The value NaN is a number. Even though NaN means "not a number", it's still got the data type "number".

The string "13t" when coerced to a number value yields NaN, unsurprisingly. Adding 1 to NaN also yields NaN.

answered May 09 '16 at 14:06

Pointy

score 3 · Answer 2 · answered May 09 '16 at 14:07

3

That is because

typeof NaN; //outpute "number"

and

+"13t" //is NaN

And second one is trying to add 1 to NaN, which is still NaN.

answered May 09 '16 at 14:07

gurvinder372

2 Answers2