regular expression for checking .css file

Question

I wanna check the file is css file or not using regular expression. I tried

new RegExp(".css$").test("a.css"); //true

but it is matching filename.acss which is correct. I want regex to match a valid .css file only. I need following cases .

new RegExp(".css$").test("a.acss"); //false
new RegExp(".css$").test(".css"); //false
new RegExp(".css$").test("a.cssa"); //false
new RegExp(".css$").test("a.css"); //true

"match a valid .css file" do you mena that the file extention as a string is .css or the file is the right mime type? — atmd
– atmd, Commented Jul 17, 2015 at 10:32
regular expressions are overkill for this simple task. simply test if the ending of the string is ".css" and if the length of the file name is >= 4. more efficient! — Willi Mentzel
– Willi Mentzel, Commented Jul 17, 2015 at 10:53
I suggest re-reading some basic regexp tutorials. You'll quickly encounter the . character which matches anything, and needs to be escaped if you mean a real period. — user663031
– user663031, Commented Jul 17, 2015 at 10:57

Tushar · Accepted Answer · 2015-07-17 11:00:15Z

2

.: (The decimal point) matches any single character except the newline character.

You need to escape . by preceding \ to match . literal.

var regex = /.\.css$/; // /\S+\.css$/; // /[\w\d]+\.css$/
regex.test("a.css");

Exaples

var regex = /.\.css$/;

alert(regex.test("a.acss")); // false
alert(regex.test(".css")); // false
alert(regex.test("a.cssa")); // false
alert(regex.test("a.css")); // true

edited Jul 17, 2015 at 11:00

answered Jul 17, 2015 at 10:32

Tushar

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9 Comments

Ashisha Nautiyal Over a year ago

it is matching to regex.test(".css"); also . which I don't want

Ashisha Nautiyal Over a year ago

bro I want to avoid .css also . 2nd test must give false

foobar Over a year ago

Just use .+\.css$ then. That requires at least one more character in front of the extension.

foobar Over a year ago

\S+\.css$ will not work for file systems that allow white spaces in file names. To have a working regex that works with any characters allowed by a file system and any character set, use .+\.css$.

Tushar Over a year ago

Downvoter, Can something be improved? Please add comment here

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