Parsing regex in javascript -

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• javascript regex, use escape characters? 3 answers

i'm unable parse regex. i've tested regexpal.com , regex101.com (by setting expression "(?:^csrf-token|;\s*csrf-token)=(.*?)(?:;|$)" , test string "__ngdebug=false; csrf-token=b2ssoj4jnolpdmxahn4corpvfoo4ngsupej25tdj") works.

the example jsfiddle.

function getcookie(name) {  			      var s = "__ngdebug=false; csrf-token=b2ssoj4jnolpdmxahn4corpvfoo4ngsupej25tdj";            var regexp = new regexp("(?:^" + name + "|;\s*"+ name + ")=(.*?)(?:;|$)", "g");      var result = regexp.exec(s);      return (result === null) ? null : result[1];  }  alert(getcookie("csrf-token"));

if s "csrf-token=b2ssoj4jnolpdmxahn4corpvfoo4ngsupej25tdj", works fine. please tell me what's wrong.

the expected output "b2ssoj4jnolpdmxahn4corpvfoo4ngsupej25tdj", , there no input (the string tested 's').

change

"|;\s*" 

to

"|;\\s*"     ^ 

the thing is, constructing regexp passing in string via constructor, need follow rule of escaping in string literal. in javascript, "\s" recognized single character string, lowercase s. specify \, need escape it.