About jQuery $. isNumeric vs. $. isNaN vs. isNaN

In jQuery, there are several ways to determine whether an object is a number or whether it can be converted to a number.
First, jQuery. isNaN () has been removed from the latest version (after 1.7) and replaced by jQuery. isNumeric (). This is not surprising, because jQuery. isNaN () has the same name as the built-in isNaN () in Javascript, but the semantics is not exactly the same, which may cause ambiguity in a certain sense. JQuery. isNumeric () has similar functions and resolves ambiguity issues.

JQuery. isNumeric () checks whether the passed parameter is a number or whether it can be converted to a number. The Javascript built-in isNaN () checks whether the passed parameter is a valid number. A typical example is 0/0.

For specific differences, see test:

Test data:

Copy codeThe Code is as follows: var values = [

"-10 ",
,
XFF,

"0xFF ",

"8e5 ",
.. 1415,

+ 10,
,

"",

{},

NaN,

Null,

True,

Infinity,

Undefined,

False

];

Use jQuery verision1.6:

Copy codeThe Code is as follows: for (var index in values ){

Var v = values [index];

$ ('Table'). append ('<tr> <td>' + v + '</td> <td>'

+ (! IsNaN (v )? "True": "false ")

+ '</Td> <td>'

+ (! $. IsNaN (v )? "True": "false ")

+ '</Td> </tr> ');

}

Output:

	! IsNaN ()	! $. IsNaN ()
-10	True	True
16	True	True
255	True	True
0xFF	True	True
8e5	True	True
3.1415	True	True
10	True	True
100	True	True
	True	False
[Object Object]	False	False
NaN	False	False
Null	True	False
True	True	False
Infinity	True	False
Undefined	False	False

Use jQuery version1.7

Copy codeThe Code is as follows: for (var index in values ){

Var v = values [index];

$ ('Table'). append ('<tr> <td>' + v + '</td> <td>'

+ (! IsNaN (v )? "True": "false ")

+ '</Td> <td>'

+ ($. IsNumeric (v )? "True": "false ")

+ '</Td> </tr> ');

}

Output:

	! IsNaN ()	$. IsNumeric ()
-10	True	True
16	True	True
255	True	True
0xFF	True	True
8e5	True	True
3.1415	True	True
10	True	True
100	True	True
	True	False
[Object Object]	False	False
NaN	False	False
Null	True	False
True	True	False
Infinity	True	False
Undefined	False	False

We can see that $. isNumeric () and! $. IsNaN () results are the same, while jQuery $. isNumeric () comes with Javascript! IsNaN () processes null strings, null, true/false, and Infinity differently. Because isNaN () only checks whether the input value is of the NaN type.

NaN (Not a Number) is a numeric data type, indicating undefined or unrepresentable value, especially the floating point value.

Therefore, isNaN (null) = false is semantically correct, because null is not NaN (in fact, null, true/false, and so on will be converted to the number 0 first ). But if yes! IsNaN () is not appropriate to determine whether the passed value can be converted to a number. Another Javascript method, typeof num = 'number', cannot detect strings. Therefore, if jQuery $. isNumeric () is not used, it is better to rewrite a method to judge, such as using regular expressions or:

Copy codeThe Code is as follows: function isNumeric (obj ){
Return! IsNaN (parseFloat (obj) & isFinite (obj );
}