javascript - Matching charset of HTTP Header Content-Type -

in javascript, want "charset" attribute of http header field name 'content-type'

the regex i've seen far has been like:

var charset = (/^charset=(.+)/im).exec(contenttype)[1]; 

with contenttype contain informations of content-type http header.

but in testing, matched result 'null'

edit: follow response @andris leduskrasts,

var ctype = 'text/html; charset=utf-8'; var charset = new regexp('charset=.*?(?=$|\s|\;|\")').exec(ctype); system.stdout.writeline(charset); 

i 'charset=utf-8'. idea 'utf-8'. ?

i experienced same problem.

if need extract charset value arbitrary content-type header (which permits characters after charset assignment per rfc1341) can use following js regexp:

var re = /charset=([^()<>@,;:\"/[\]?.=\s]*)/i; 

this works because matched group starts after = , excludes possible endings of charset specification given in link; namely ()<>@,;:\"/[]?.=, spaces, , (implicitly) end-of-string.

since charset optional, can set appropriate value like:

var charset = re.test(ctype) ? re.exec(ctype)[1] : 'utf8'; 

or other default.