Validate currency amount using regular expressions in JavaScript [duplicate] - javascript

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What's a C# regular expression that'll validate currency, float or integer?
How can I validate currency amount using regular expressions in JavaScript?
Decimals separator: ,
Tens, hundreds, etc. separator: .
Pattern: ###.###.###,##
Examples of valid amounts:
1
1234
123456
1.234
123.456
1.234.567
1,23
12345,67
1234567,89
1.234,56
123.456,78
1.234.567,89
EDIT
I forgot to mention that the following pattern is also valid: ###,###,###.##

Based solely on the criteria you gave, this is what I came up with.
/(?:^\d{1,3}(?:\.?\d{3})*(?:,\d{2})?$)|(?:^\d{1,3}(?:,?\d{3})*(?:\.\d{2})?$)/
http://refiddle.com/18u
It is ugly, and it will only get worse as you find more cases that need to be matched. You'd be well served to find and use some validation library rather than try to do this all yourself, especially not in a single regular expression.
Updated to reflect added requirements.
Updated again in regard to comment below.
It would match 123.123,123 (three trailing digits instead of two) because it would accept either comma or period as both the thousands and decimal separators. To fix that, I've now essentially doubled up the expression; either it matches the whole thing with commas for separators and a period as the radix point, or it matches the whole thing with periods for separators and a comma as the radix point.
See what I mean about it getting messier? (^_^)
Here's the verbose explanation:
(?:^ # beginning of string
\d{1,3} # one, two, or three digits
(?:
\.? # optional separating period
\d{3} # followed by exactly three digits
)* # repeat this subpattern (.###) any number of times (including none at all)
(?:,\d{2})? # optionally followed by a decimal comma and exactly two digits
$) # End of string.
| # ...or...
(?:^ # beginning of string
\d{1,3} # one, two, or three digits
(?:
,? # optional separating comma
\d{3} # followed by exactly three digits
)* # repeat this subpattern (,###) any number of times (including none at all)
(?:\.\d{2})? # optionally followed by a decimal perioda and exactly two digits
$) # End of string.
One thing that makes it look more complicated is all the ?: in there. Normally a regular expression captures (returns matches for) all of the subpatterns too. All ?: does is say to not bother to capture the subpattern. So technically, the full thing would still match your entire string if you took all of the ?: out, which looks a bit clearer:
/(^\d{1,3}(\.?\d{3})*(,\d{2})?$)|(^\d{1,3}(,?\d{3})*(\.\d{2})?$)/
Also, regular-expressions.info is a great resource.

This works for all your examples:
/^(?:\d+(?:,\d{3})*(?:\.\d{2})?|\d+(?:\.\d{3})*(?:,\d{2})?)$/
As a verbose regex (not supported in JavaScript, though):
^ # Start of string
(?: # Match either...
\d+ # one or more digits
(?:,\d{3})* # optionally followed by comma-separated threes of digits
(?:\.\d{2})? # optionally followed by a decimal point and exactly two digits
| # ...or...
\d+ # one or more digits
(?:\.\d{3})* # optionally followed by point-separated threes of digits
(?:,\d{2})? # optionally followed by a decimal comma and exactly two digits
) # End of alternation
$ # End of string.

This handles everything above except for the (just added?) 123.45 case:
function foo (s) { return s.match(/^\d{1,3}(?:\.?\d{3})*(?:,\d\d)?$/) }
Do you need to handle multiple separator formats?

Related

Limit 10 characters is numbers and only 1 dot

I'm having a regex problem when input
That's the requirement: limit 10 characters (numbers) including dots, and only 1 dot is allowed
My current code is only 10 characters before and after the dot.
^[0-9]{1,10}\.?[0-9]{0,10}$
thank for support.
You could assert 10 chars in the string being either . or a digit.
Then you can match optional digits, and optionally match a dot and again optional digits:
^(?=[.\d]{10}$)\d*(?:\.\d*)?$
The pattern matches:
^ Start of string
(?=[.\d]{10}$) Positive lookahead, assert 10 chars . or digit till the end of string
\d* Match optional digits
(?:\.\d*)? Optionally match a `. and optional digits
$ End of string
See a regex demo.
If the pattern should not end on a dot:
^(?=[.\d]{10}$)\d*(?:\.\d+)?$
Regex demo
The decimal point throws a wrench into most single pattern approaches. I would probably use an alternation here:
^(?:\d{1,10}|(?=\d*\.)(?!\d*\.\d*\.)[0-9.]{2,11})$
This pattern says to match:
^ from the start of the number
(?:
\d{1,10} a pure 1 to 10 digit integer
| OR
(?=\d*\.) assert that one dot is present
(?!\d*\.\d*\.) assert that ONLY one dot is present
[0-9.]{2,11} match a 1 to 10 digit float
)
$ end of the number
You can use a lookahead to achieve your goals.
First, looking at your regex, you've used [0-9] to represent all digit characters. We can shorten this to \d, which means the same thing.
Then, we can focus on the requirement that there be only one dot. We can test for this with the following pattern:
^\d*\.?\d*$
\d* means any number of digit characters
\.? matches one literal dot, optionally
\d* matches any number of digit characters after the dot
$ anchors this to the end of the string, so the match can't just end before the second dot, it actually has to fail if there's a second dot
Now, we don't actually want to consume all the characters involved in this match, because then we wouldn't be able to ensure that there are <=10 characters. Here's where the lookahead comes in: We can use the lookahead to ensure that our pattern above matches, but not actually perform the match. This way we verify that there is only one dot, but we haven't actually consumed any of the input characters yet. A lookahead would look like this:
^(?=\d*\.?\d*$)
Next, we can ensure that there are aren't more than 10 characters total. Since we already made sure there are only dots and digits with the above pattern, we can just match up to 10 of any characters for simplicity, like so:
^.{1,10}$
Putting these two patterns together, we get this:
^(?=\d*\.?\d*$).{1,10}$
This will only match number inputs which have 10 or fewer characters and have no more than one dot.
If you would like to ensure that, when there is a dot, there is also a digit accompanying it, we can achieve this by adding another lookahead. The only case that meets this condition is when the input string is just a dot (.), so we can just explicitly rule this case out with a negative lookahead like so:
(?!\.$)
Adding this back in to our main expression, we get:
^(?=\d*\.?\d*$)(?!\.$).{1,10}$

Get all prices with $ from string into an array in Javascript

var string = 'Our Prices are $355.00 and $550, down form $999.00';
How can I get those 3 prices into an array?
The RegEx
string.match(/\$((?:\d|\,)*\.?\d+)/g) || []
That || [] is for no matches: it gives an empty array rather than null.
Matches
$99
$.99
$9.99
$9,999
$9,999.99
Explanation
/ # Start RegEx
\$ # $ (dollar sign)
( # Capturing group (this is what you’re looking for)
(?: # Non-capturing group (these numbers or commas aren’t the only thing you’re looking for)
\d # Number
| # OR
\, # , (comma)
)* # Repeat any number of times, as many times as possible
\.? # . (dot), repeated at most once, as many times as possible
\d+ # Number, repeated at least once, as many times as possible
)
/ # End RegEx
g # Match all occurances (global)
To match numbers like .99 more easily I made the second number mandatory (\d+) while making the first number (along with commas) optional (\d*). This means, technically, a string like $999 is matched with the second number (after the optional decimal point) which doesn’t matter for the result — it’s just a technicality.
A non-regex approach: split the string and filter the contents:
var arr = string.split(' ').filter(function(val) {return val.startsWith('$');});
Use match with regex as follow:
string.match(/\$\d+(\.\d+)?/g)
Regex Explanation
/ : Delimiters of regex
\$: Matches $ literal
\d+: Matches one or more digits
()?: Matches zero or more of the preceding elements
\.: Matches .
g : Matches all the possible matching characters
Demo
This will check if there is a possible decimal digits following a '$'

regular expression to replace with ','

I have one RegExp, could anyone explain exactly what it does?
Regexp
b=b.replace(/(\d{1,3}(?=(?:\d\d\d)+(?!\d)))/g,"$1 ")
I think it is replacing with space(' ')
if i'm right, i want to replace it with comma(,) instead of space(' ').
To explain the regex, let's break it down:
( # Match and capture in group number 1:
\d{1,3} # one to three digits (as many as possible),
(?= # but only if it's possible to match the following afterwards:
(?: # A (non-capturing) group containing
\d\d\d # exactly three digits
)+ # once or more (so, three/six/nine/twelve/... digits)
(?!\d) # but only if there are no further digits ahead.
) # End of (?=...) lookahead assertion
) # End of capturing group
Actually, the outer parentheses are unnecessary if you use $& instead of $1 for the replacement string ($& contains the entire match).
The regex (\d{1,3}(?=(?:\d\d\d)+(?!\d))) matches any 1-3 digits ((\d{1,3}) that is followed by a multiple of 3 digits ((?:\d\d\d)+), that isn't followed by another digit ((?!\d)). It replaces it with "$1 ". $1 is replaced by the first capture group. The space behind it is... a space.
See regexpressions on mdn for more information about the different syntaxes.
If you want to seperate the numbers with a comma, instead of a space, you'll need to replace it with "$1," instead.
Don't try to solve everything by using regular expressions.
Regular expressions are meant for matching, not to fix non-text-encoded-as-text formatting.
If you want to format numbers differently, extract them and use format strings to reformat them on a character processing level. That is just an ugly hack.
It is okay to use regular expressions to find the numbers in the text, e.g. \d{4,} but trying to do the actual formatting with regexp is a crazy abuse.

Regular expression for allow - not more then 2 times

i am using ^(^[a-z]?[a0-z9]+[.|-][a0-z9]+[a-z]+[.|-][a0-z9]+[a-z]?$)+$ , this force user type 2 hyphen(-) in his expression ....
But i need that regular expression can allow maximum 2 hypen and minimum one hyphen in his expression....
This is a simple re implementation.
/^[^-]+(-[^-]+){1,2}$/
And the test result:
"123".match(/^[^-]+(-[^-]+){1,2}$/)
null
"123-123".match(/^[^-]+(-[^-]+){1,2}$/)
["123-123", "-123"]
"123-123-123".match(/^[^-]+(-[^-]+){1,2}$/)
["123-123-123", "-123"]
"123-123-123-123".match(/^[^-]+(-[^-]+){1,2}$/)
null
And if you just copy one from other, then you should try to write one by yourself.
If not, you should delete it and restart.
^[^-]*-+[^-]*-{0,1}[^-]*$
String1: abc-pqr,
String2: aaa-bbb,
String3 aaa-bbb-ccc-ddd,
where String 1 and 2 are valid and 3 is invalid?
This allows String 1 and 2. But not 3.
This regex should work...
/^[^-]*-[^-]*-[^-]*$/
It works by capturing anything except a hyphen (zero or more times), then a hyphen, then anything else again, then another hyphen, then anything else. It has a start and end marker to ensure that the whole string does not contain any more hyphens.
Breaks down like this...
/ # begin regex
^ # start of string
[^-]* # not hyphen ([^-]), zero or more times (*)
- # hyphen
[^-]* # not hyphen ([^-]), zero or more times (*)
- # hyphen
[^-]* # not hyphen ([^-]), zero or more times (*)
$ # end of string
/ # end regex

Regex validation for comma separated string

I need to validate and input string client side.
Here is an example of the string:
1:30-1:34, 1:20-1:22, 1:30-1:37,
It's basically time codes for a video.
Can this be done with regex?
Banging my head against the wall...
^(?:\b\d+:\d+-\d+:\d+\b(?:, )?)+$
would probably work; at least it matches your example. But you might need to add a few edge cases to make the rules for matching/not matching clearer.
^ # Start of string
(?: # Try to match...
\b # start of a "word" (in this case, number)
\d+ # one or more digits
: # a :
\d+ # one or more digits
- # a dash
\d+ # one or more digits
: # a :
\d+ # one or more digits
\b # end of a "word"
(?:, )? # optional comma and space
)+ # repeat one or more times
$ # until the end of the string
The following is a simple representation. I have assumed that the string has the exact same form as you have shown. This may be a good starting point for you. I'll improve the regex if you provide more specific requirements.
([0-9]+:[0-9]{1,2}-[0-9]+:[0-9]{1,2},\w*)+
Explanation (inspired from Tim above)
[0-9]+   #One ore more digits
:      # A colon
[0-9]{1,2}  #A single digit or a pair of digits
-       #A dash
,       #A comma
\w*      #Optional whitespace

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