Comparing String with Integer in javascript

Question

While working in my JS code today, I found the following situation and can not explain myself what should be the correct output ?

'sachin' > 2 // False

'sachin' < 2 // False

'sachin' == 2 // False

I expect result of either of < or > should be true. What am I missing ?

Answer 1

When the runtime attempts to convert 'sachin' to a number, it will fail and end up as NaN. That special constant results in false for any comparison to any other numeric value. The NaN constant ("Not A Number") is not equal to any other value, nor is it less than or greater than any other value.

edit — the ==, <, and > operators all "prefer" numbers to strings. If one operand is a number and the other a string, they'll always try to interpret the string as a number. It doesn't matter what order the operands appear in; what matters is the operand types.

(Strictly speaking, the results of < and > when NaN is involved are supposed to be undefined, according to the spec, but Firefox seems to give false instead.)