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RegExp avoid double space and space before characters

I'm trying to write a regular expression in order to not allow double spaces anywhere in a string, and also force a single space before a MO or GO mandatory, with no space allowed at the beginning and at the end of the string.
Example 1 : It is 40 GO right
Example 2 : It is 40GO wrong
Example 3 : It is 40 GO wrong
Here's what I've done so far ^[^ ][a-zA-Z0-9 ,()]*[^;'][^ ]$, which prevents spaces at the beginning and at the end, and also the ";" character. This one works like a charm.
My issue is not allowing double spaces anywhere in the string, and also forcing spaces right before MO or GO characters.
After a few hours of research, I've tried these (starting from the previous RegExp I wrote):
To prevent the double spaces: ^[^ ][a-zA-Z0-9 ,()]*((?!.* {2}).+)[^;'][^ ]$
To force a single space before MO: ^[^ ][a-zA-Z0-9 ,()]*(?=\sMO)*[^;'][^ ]$
But neither of the last two actually work. I'd be thankful to anyone that helps me figure this out

The lookahead (?!.* {2} can be omitted, and instead start the match with a non whitespace character and end the match with a non whitespace character and use a single space in an optionally repeated group.
If the string can not contain a ' or ; then using [^;'][^ ]$ means that the second last character should not be any of those characters.
But you can omit that part, as the character class [a-zA-Z0-9,()] does not match ; and '
Note that using a character class like [^ ] and [^;'] actually expect a single character, making the pattern that you tried having a minimum length.
Instead, you can rule out the presence of GO or MO preceded by a non whitespace character.
^(?!.*\S[MG]O\b)[a-zA-Z0-9,()]+(?: [a-zA-Z0-9,()]+)*$
The pattern matches:
^ Start of string
(?!.*\S[MG]O\b) Negative lookahead, assert not a non whitspace character followed by either MO or GO to the right. The word boundary \b prevents a partial word match
[a-zA-Z0-9,()]+ Start the match with 1+ occurrences of any of the listed characters (Note that there is no space in it)
(?: [a-zA-Z0-9,()]+)* Optionally repeat the same character class with a leading space
$ End of string
Regex demo

RegEx for matching all chars except for comma separated digits

I have an input that I want to apply validation to. User can type any integer (positive or negative) numbers separated with a comma. I want to
Some examples of allowed inputs:
1,2,3
-1,2,-3
3
4
22,-33
Some examples of forbidden inputs:
1,,2
--1,2,3
-1,2,--3
asdas
[]\%$1
I know a little about regex, I tried lots of ways, they're not working very well see this inline regex checker:
^[-|\d][\d,][\d]

You can use
^(?:-?[0-9]+(?:,(?!$)|$))+$
https://regex101.com/r/PAyar7/2
-? - Lead with optional -
[0-9]+ - Repeat digits
(?:,(?!$)|$)) - After the digits, match either a comma, or the end of the string. When matching a comma, make sure you're not at the end of the string with (?!$)

As per your requirements I'd use something simple like
^-?\d+(?:,-?\d+)*$
at start ^ an optional minus -? followed by \d+ one or more digits.
followed by (?:,-?\d+)* a quantified non capturing group containing a comma, followed by an optional hyphen, followed by one or more digits until $ end.
See your updated demo at regex101
Another perhaps harder to understand one which might be a bit less efficient:
^(?:(?:\B-)?\d+,?)+\b$
The quantified non capturing group contains another optional non capturing group with a hyphen preceded by a non word boundary, followed by 1 or more digits, followed by optional comma.
\b the word boundary at the $ end ensures, that the string must end with a word character (which can only be a digit here).
You can test this one here at regex101

Issues in password regular expression

Hi all I am making a password regular expression in javascript test() method, It will take the following inputs
solution
/^(?=.*\d)^(?=.*[!#$%'*+\-/=?^_{}|~])(?=.*[A-Z])(?=.*[a-z])\S{8,15}$/gm
May contains any letter except space
At least 8 characters long but not more the 15 character
Take at least one uppercase and one lowercase letter
Take at least one numeric and one special character
But I am not able to perform below task with (period, dot, fullStop)
(dot, period, full stop) provided that it is not the first or last character, and provided also that it does not appear two or more times consecutively.
Can anyone one help me to sort out this problem, Thanks in advance

You may move the \S{8,15} part with the $ anchor to the positive lookahead and place it as the first condition (to fail the whole string if it has spaces, or the length is less than 8 or more than 15) and replace that pattern with [^.]+(?:\.[^.]+)* consuming subpattern.
/^(?=\S{8,15}$)(?=.*\d)(?=.*[!#$%'*+\/=?^_{}|~-])(?=.*[A-Z])(?=.*[a-z])[^.]+(?:\.[^.]+)*$/
See the regex demo
Details:
^ - start of string
(?=\S{8,15}$) - the first condition that requires the string to have no whitespaces and be of 8 to 15 chars in length
(?=.*\d) - there must be a digit after any 0+ chars
(?=.*[!#$%'*+\/=?^_{}|~-]) - there must be one symbol from the defined set after any 0+ chars
(?=.*[A-Z]) - an uppercase ASCII letter is required
(?=.*[a-z]) - a lowercase ASCII letter is required
[^.]+(?:\.[^.]+)* - 1+ chars other than ., followed with 0 or more sequences of a . followed with 1 or more chars other than a dot (note that we do not have to add \s into these 2 negated character classes as the first lookahead already prevalidated the whole string, together with its length)
$ - end of string.

Regex allow multiple work in a sentence

I'm trying to parse following sentences with regex (javascript) :
I wish a TV
I want some chocolate
I need fire
Currently I'm trying : I(\b[a-zA-Z]*\b){0,5}(TV|chocolate|fire) but it doesn't work. I also made some test with \w but no luck.
I want to allow any word (max 5 words) between "I" and the last word witch is predefined.

To account for non-word chars in-between words, you may use
/I(?:\W+\w+){0,5}\‌​W+(?:TV|chocolate|fir‌​e)/
See the regex demo
The point is that you added word boundaries, but did not account for spaces, punctuation, etc. (all the other non-word chars) between "words".
Pattern details:
I - matches the left delimiter
(?:\W+\w+){0,5}\‌​W+ - matches 0 to 5 sequences (due to the limiting quantifier {n,m}) of 1+ non-word chars (\W+) and 1+ word chars after them (\w+), and a \W+ at the end matches 1 or more non-word chars that must be present to separate the last matched word chars from the...
(?:TV|chocolate|fir‌​e) - matches the trailing delimiter

You need to add the whitespace after the I. Otherwise it wouldn´t capture the whole sentence.
I(\b[a-zA-Z ]*\b){0,5}(TV|chocolate|fire)
I greate site to test regex expressions is regexr

If you don't care about the spaces, use:
/I(\s[a-zA-Z]*\s?){0,5}(TV|chocolate|fire)/

Try
/I\s+(?:\w+\s+){0,5}(TV|chocolate|fire)/
(Test here)
Based on Stefan Kert version, but rely on right side spaces of each extra word instead of word boundaries.
It also accepts any valid "word" (\w) character words of any length and any valid spacing character (not caring for repetitions).

Explain this regex js

I'm using this regex to match some strings:
^([^\s](-)?(\d+)?(\.)?(\d+)?)$/
I'm confusing about why it's permitted to enter two dots, like ..
What I understand is that only allowed to put 1 dash or none (-)?
Any digits with no limit or none (\d+)?
One dot or none (\.)?
Why is allowed to put .. or even .4.6?
Testing done in http://www.regextester.com/

[^\s] means anything that is not a whitespace. This includes dots. Trying to match .. will get you:
[^\s] matches .
(-)? doesn't match
(\d+)? doesn't match
(\.)? matches .
(\d+)? doesn't match
I'll assume you wanted to match numbers (possibly negative/floating):
^-?\d+(\.\d+)?$

^([^\s](-)?(\d+)?(\.)?(\d+)?)$/
Assert position at the beginning of the string ^
Match the regex below and capture its match into backreference number 1 ([^\s](-)?(\d+)?(\.)?(\d+)?)
Match any single character that is NOT present in the list below and that is NOT a line break character (line feed) [^\s]
A single character from the list “\s” (case sensitive) \s
Match the regex below and capture its match into backreference number 2 (-)?
Between zero and one times, as few or as many times as needed to find the longest match in combination with the other quantifiers or alternatives ?
Match the character “-” literally -
Match the regex below and capture its match into backreference number 3 (\d+)?
Between zero and one times, as few or as many times as needed to find the longest match in combination with the other quantifiers or alternatives ?
MySQL does not support any shorthand character classes \d+
Between one and unlimited times, as few or as many times as needed to find the longest match in combination with the other quantifiers or alternatives +
Match the regex below and capture its match into backreference number 4 (\.)?
Between zero and one times, as few or as many times as needed to find the longest match in combination with the other quantifiers or alternatives ?
Match the character “.” literally \.
Match the regex below and capture its match into backreference number 5 (\d+)?
Between zero and one times, as few or as many times as needed to find the longest match in combination with the other quantifiers or alternatives ?
MySQL does not support any shorthand character classes \d+
Between one and unlimited times, as few or as many times as needed to find the longest match in combination with the other quantifiers or alternatives +
Assert position at the very end of the string $
Match the character “/” literally /
Created with RegexBuddy

As I mentioned in my comment, [^\n] is a negated character class that matches .. and as there is another (\.)? pattern, the regex can match 2 consecutive dots (since all of the parts except for [^\s] are optional).
In order not to match strings like .4.5 or .. you just need to add the . to the [^\n] negated character class:
^([^\s.](-)?(\d+)?(\.)?(\d+)?)$
^
See demo. This will not let any . in the initial capturing group.
You can use a lookahead to only disallow the first character as a dot:
^(?!\.)([^\s](-)?(\d+)?(\.)?(\d+)?)$
See another demo
All explanation is available at the online regex testers:
In order to match the numbers in the format you expect, use:
^(?:[-]?\d+\.?\d*|-)$
Human-readable explanation:
^ - start of string and then there are 2 alternatives...
[-]? - optional hyphen
\d+ - 1 or more digits
\.? - optional dot
\d* - 0 or more digits
| -OR-
- - a hyphen
$ - end of string
See demo