compare string with numbers in javascript

[Matt]

if (123 > 33) will return true

and

if ("123" > 33) will return true

So my question is, if the above behaviors are the same?? If string is
a number, and
compare with another number, it will be the same behavior as compare 2
numbers?

In this case, it is comparing 2 strings that are numbers, so they are
string comparisons here.
correct?

if ("123" > "33") will return true

In this case, "33a" is not a number, that's why when it compare with
another number, it
always return false. correct?

if ("33a" > 33) will return false

please advise. thanks!!

 

[Lasse Reichstein Nielsen]

if (123 > 33) will return true

and

if ("123" > 33) will return true
Correct.

So my question is, if the above behaviors are the same?? If string
is a number, and compare with another number, it will be the same
behavior as compare 2 numbers?

Yes. The "greater than" comparison operator, when given a number and
another argument, will convert the other argument to a number. The
conversion is the same as what the Number function does.

In this case, it is comparing 2 strings that are numbers, so they are
string comparisons here.
correct?

Correct. If *both* arguments are strings, the comparsion is lexical
comparison.

if ("123" > "33") will return true

The result of ("123" > "33") is false, since the first character of
the first string is smaller than the first character of the second
string.

In this case, "33a" is not a number, that's why when it compare with
another number, it always return false. correct?

Correct, because (Number("33a")) yields NaN, and (NaN > 33) is false.

/L

 

[Grant Wagner]

Correct, because (Number("33a")) yields NaN, and (NaN > 33) is false.

Actually, (Number.NaN < 33) is false as well. As is (Number.NaN == Number.NaN).

(Number.NaN != Number.NaN) is true, which goes against common sense, but it's
the documented behaviour:

<url:
http://devedge.netscape.com/library/manuals/2000/javascript/1.3/reference/number.html#1193302
/>
<url: http://msdn.microsoft.com/library/en-us/jscript7/html/jspronannumber.asp
/>

 

[Lasse Reichstein Nielsen]

Actually, (Number.NaN < 33) is false as well. As is (Number.NaN ==
Number.NaN).

(Number.NaN != Number.NaN) is true, which goes against common sense,

I'd say that (NaN == NaN) being false is what goes against common sense.
From that, I find it entirely logical that
(NaN != NaN) is the same as !(NaN == NaN)

/L