正则表达式：否定集中的单个字符实例

Question

Is there any possible way to limit a character in a negated set to a single instance?

What I am working with: [^0-9\\.]

This wont match numbers and decimals, but is there any way to limit to a single decimal?

So it wont match:

84.34356
.3948

but will match:

86..3232
   ^
84.54.23.
     ^  ^

This way

val.replace(/[^0-9\.]/g, '')

would replace the matched characters

Answer 1

Using split , shift and join :

var s = '84.54.23.'
var arr = s.split(/\./).filter(Boolean)

if (arr.length > 1)
   s = arr.shift() + '.' + arr.join('')
//=> s="84.5423"

s = '86..3232'
arr = s.split(/\./).filter(Boolean)
if (arr.length > 1)
   s = arr.shift() + '.' + arr.join('')
//=> s="86.3232"

s = '84.34356'
arr = s.split(/\./).filter(Boolean)
if (arr.length > 1)
   s = arr.shift() + '.' + arr.join('')
//=> s="84.34356"

s = '.3948'
arr = s.split(/\./).filter(Boolean)
if (arr.length > 1)
   s = arr.shift() + '.' + arr.join('')
//=> s=".3948"

Answer 2

Description

^([0-9]+[.](?=[.]+)|[0-9]+[.][0-9]+|[.][0-9]+)|(?<=[0-9])[.]|[.](?=[0-9]|$)

Replace with: $1

This regular expression will do the following:

• replace unwanted decimal points found in or around numbers
• leave the decimal points around regular text

Example

Live Demo

https://regex101.com/r/pF4aS3/2

Sample text

84.34356
.3948
but will match.:

86..3232
84.54.23.

After Replacement

84.34356
.3948
but will match.:

86.3232
84.5423

Explanation

NODE                     EXPLANATION
----------------------------------------------------------------------
  ^                        the beginning of the string
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    [0-9]+                   any character of: '0' to '9' (1 or more
                             times (matching the most amount
                             possible))
----------------------------------------------------------------------
    [.]                      any character of: '.'
----------------------------------------------------------------------
    (?=                      look ahead to see if there is:
----------------------------------------------------------------------
      [.]+                     any character of: '.' (1 or more times
                               (matching the most amount possible))
----------------------------------------------------------------------
    )                        end of look-ahead
----------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------
    [0-9]+                   any character of: '0' to '9' (1 or more
                             times (matching the most amount
                             possible))
----------------------------------------------------------------------
    [.]                      any character of: '.'
----------------------------------------------------------------------
    [0-9]+                   any character of: '0' to '9' (1 or more
                             times (matching the most amount
                             possible))
----------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------
    [.]                      any character of: '.'
----------------------------------------------------------------------
    [0-9]+                   any character of: '0' to '9' (1 or more
                             times (matching the most amount
                             possible))
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
 |                        OR
----------------------------------------------------------------------
  (?<=                     look behind to see if there is:
----------------------------------------------------------------------
    [0-9]                    any character of: '0' to '9'
----------------------------------------------------------------------
  )                        end of look-behind
----------------------------------------------------------------------
  [.]                      any character of: '.'
----------------------------------------------------------------------
 |                        OR
----------------------------------------------------------------------
  [.]                      any character of: '.'
----------------------------------------------------------------------
  (?=                      look ahead to see if there is:
----------------------------------------------------------------------
    [0-9]                    any character of: '0' to '9'
----------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------
    $                        before an optional \n, and the end of
                             the string
----------------------------------------------------------------------
  )                        end of look-ahead
----------------------------------------------------------------------