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I am using Nodejs to build application in which I need to process certain strings I have used the JS "RegExp" object for this purpose. I want only a part of my string in the regex to be case insensitive
var key = '(?i)c(?-i)ustomParam';
var find = '\{(\\b' + key +'\\b:?.*?)\}';
var regex = new RegExp(find,"g");
But it breaks with following error
SyntaxError: Invalid regular expression: /{(\b(?i)c(?-i)ustomParam\b:?.*?)}/
I will get the key from some external source like redis and the string to be matched from some other external source , I want that the first alphabet should be case-Insensitive and the rest of alphabets to be case-Sensitive.
When I get the key from external source I will append the (?i) before the first alphabet and (?-i) after the first alphabet.
I even tried this just for starters sake, but that also didn't work
var key ='customParam';
var find = '(?i)\{(\\b' + key +'\\b:?.*?)\}(?-i)';
var regex = new RegExp(find,"g");
I know I can use "i" flags instead of above ,but that's not my use case. I did it just to check.
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Perl lets you make part of your regular expression case-insensitive by using the (? i:) pattern modifier. Modern regex flavors allow you to apply modifiers to only part of the regular expression.
In Java, by default, the regular expression (regex) matching is case sensitive. To enable the regex case insensitive matching, add (?) prefix or enable the case insensitive flag directly in the Pattern.
Regular expression, or simply RegEx JavaScript allows you to write specific search patterns. You can also make the search case-sensitive or insensitive, search for a single JavaScript RegEx match or multiple, look for characters at the beginning or the end of a word.
To do case insensitive search, you can use regular expressions and the String#match() function, or you can convert both the string and substring to lower case using the String#toLowerCase() function.
JavaScript built-in RegExp does not support inline modifiers, like (?im), let alone inline modifier groups that can be placed anywhere inside the pattern (like (?i:....)).
Even XRegExp cannot offer this functionality, you can only use (?i) on the whole pattern declaring it at the pattern beginning.
In XRegExp, you can define the regex ONLY as
var regex = XRegExp('(?i)\\{(\\b' + key +'\\b:?.*?)\\}', 'g');
On May 27, 2020, still neither JavaScript native RegExp, nor XRegExp patterns support inline modifier groups (i.e. (?i:...)), nor placing them in any part of the pattern (as far as XRegExp is concerned).
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