How can I extract a URL from url(“http://www.example.com”)?

Question

I need to get the URL of an element's background image with jQuery:

var foo = $('#id').css('background-image');

This results in something like url("http://www.example.com/image.gif") . How can I get just the "http://www.example.com/image.gif" part from that? typeof foo says it's a string, but the url() part makes me think that JavaScript and/or jQuery has a special URL type and that I should be able to get the location with foo.toString() . That doesn't work though.

Answer 1

You might want to consider regular expressions in this case:

var urlStr = 'url("http://www.foo.com/")';
var url = urlStr.replace(/^url\(['"]?([^'"]*)['"]?\);?$/, '$1');

This particular regex allows you to use formats like url(http://foo.bar/) or url("http://foo.bar/") , with single quotes instead of double quotes, or possibly with a semicolon at the end.

Answer 2

Note that different browser implementations may return the string in a different format. For instance, one browser may return double-quotes while another browser may return the value without quotes. This makes it awkward to parse, especially when you consider that quotes are valid as URL characters.

I would say the best approach is a good old check and slice() :

var imageUrlString = $('#id').css('background-image'),
    quote = imageUrlString.charAt(4),
    result;

if (quote == "'" || quote == '"')
    result = imageUrlString.slice(5, -2);
else
    result = imageUrlString.slice(4, -1);

Assuming the browser returns a valid string, this wouldn't fail. Even if an empty string were returned (ie, there is no background image), the result is an empty string.

Answer 3

You could split the string at each " and get the second element:

var foo = $('#id').css('background-image').split('"')[1];

Note: This doesn't work if your URL contains quotation marks.

Answer 4

There is no special URL type - it's a string representing a CSS url value. You can get the URL back out with a regex:

var foo = ${'#id').css('background-image');
var url = foo.match(/url\(['"](.*)['"]\)/)[1];

(that regex isn't foolproof, but it should work against whatever jQuery returns)

Answer 5

If it's always the same, I'd just take the substring of the URL without the prefix.

For instance, if it's always:

url("<URL>")
url("<otherURL>")

It's always the 5th index of the string to the len - 2

Not the best by all means, but probably faster than a Regex if you're not worried about other string formats.