RegEx for no whitespace at the beginning and end but allows all special characters , spaces , lowerc-CodePudding

I wanted to design an regex for not allowing whitespace at the beginning and at the end of a string, but allows all special characters , spaces , lowercase and uppercase alphabets and numbers in between

The regex I tried is :

'^[A-Za-z0-9 _]*[A-Za-z0-9][A-Za-z0-9 _]*$'

I am using it as a pattern validator inside input in angular as : pattern ="^[A-Za-z0-9 _]*[A-Za-z0-9][A-Za-z0-9 _]*$'"

anyhelp would be greatly appreciated

CodePudding user response：

You need either

Validators.pattern('\\S(?:.*\\S)?')

Validators.pattern(/^\S(?:.*\S)?$/)

In both cases, the regex is ^\S(?:.*\S)?$ and matches

^ - start of string
\S - any char other than whitespace
(?:.*\S)? - an optional occurrence of any zero or more chars other than line break chars as many as possible and then a non-whitespace char
$ - end of string.

CodePudding user response：

All the ASCII alphabets and special characters are defined with [!-\[\]-~]

By making sure the first and optional last is this class is all that's needed.

^[!-\[\]-~] (?:[^\S\r\n]*[!-\[\]-~])*$

https://regex101.com/r/JpsOvy/1

 ^ 
 [!-\[\]-~]  
 (?: [^\S\r\n]* [!-\[\]-~] )*
 $

[^\S\r\n] is just non-linefeed white space. Replace with \s if needed.