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Running the unit tests against the new code and it only fails on the infinity and boolean literals, and the only time that should be a problem is if you're generating code (really, who would type in a literal and check if it's numeric? It's definitely not the shortest possible regular expression, but I believe it catches all the finer subtleties of Java Script's number syntax.

You should The accepted answer failed your test #7 and I guess it's because you changed your mind. function is Number(n) function is Finite Number(n) function is Comparable Number(n) is Finite Number('Na N') false is Finite Number('Ox FF') true is Number('Na N') true is Number(1/0-1/0) true is Comparable Number('Na N') false is Comparable Number('Infinity') true Explained: Create a copy of itself, then converts the number into float, then compares itself with the original number, if it is still a number, (whether integer or float) , and matches the original number, that means, it is indeed a number. I realize this has been answered many times, but the following is a decent candidate which can be useful in some scenarios.

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During some projects I have needed to validate some data and be as certain as possible that it is a javascript numerical value that can be used in mathematical operations. The idea here is that every number or integer has one "canonical" string representation, and every non-canonical representation should be rejected.Java Script numbers are always stored as double precision floating point numbers, following the international IEEE 754 standard. This format stores numbers in 64 bits, where the number (the fraction) is stored in bits 0 to 51, the exponent in bits 52 to 62, and the sign in bit 63: By default, Java Script displays numbers as base 10 decimals. Client side validation is performed by a web browser, before input is sent to a web server.This site uses cookies to deliver our services and to show you relevant ads and job listings.We'll check each key event individually against each character, which the user enters in the textbox.Sometimes situations arise (input a phone number, zip code or credit card number) when the user should fill a single or more than one fields with numbers (0-9) in an HTML form.Next, the match() method of the string object is used to match the said regular expression against the input value. HTML Code An integer with an optional leading plus( ) or minus(-) sign To get a string contains only numbers (0-9) with a optional or - sign (e.g.1223, -4567, 1223, 4567) we use the regular expression (/^[- ]? Next, the match() method of the string object is used to match the said regular expression against the input value. Also note that it falls down on your 0x89f test, but that's because in many environments that's an okay way to define a number literal.If you want to catch that specific scenario you could add an additional check. Simply trimming the string before the length check will handle this case. is Na N('blah') ""); // false $Numeric('-1'); // true $Numeric('-1.5'); // true $Numeric('0'); // true $Numeric('0.42'); // true $Numeric('.42'); // true $Numeric('0x89f'); // true (valid hexa number) $Numeric('99,999'); // false $Numeric('#abcdef'); // false $Numeric('1.2.3'); // false $Numeric(''); // false $Numeric('blah'); // false (because they are not actually part of the number as far as I concerned, they are separate operators): I needed this for a tokenizer, where sending the number to Java Script for evaluation wasn't an option...

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