urls.js
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/**
* When source maps are enabled, `style-loader` uses a link element with a data-uri to
* embed the css on the page. This breaks all relative urls because now they are relative to a
* bundle instead of the current page.
*
* One solution is to only use full urls, but that may be impossible.
*
* Instead, this function "fixes" the relative urls to be absolute according to the current page location.
*
* A rudimentary test suite is located at `test/fixUrls.js` and can be run via the `npm test` command.
*
*/
module.exports = function (css) {
// get current location
var location = typeof window !== "undefined" && window.location;
if (!location) {
throw new Error("fixUrls requires window.location");
}
// blank or null?
if (!css || typeof css !== "string") {
return css;
}
var baseUrl = location.protocol + "//" + location.host;
var currentDir = baseUrl + location.pathname.replace(/\/[^\/]*$/, "/");
// convert each url(...)
/*
This regular expression is just a way to recursively match brackets within
a string.
/url\s*\( = Match on the word "url" with any whitespace after it and then a parens
( = Start a capturing group
(?: = Start a non-capturing group
[^)(] = Match anything that isn't a parentheses
| = OR
\( = Match a start parentheses
(?: = Start another non-capturing groups
[^)(]+ = Match anything that isn't a parentheses
| = OR
\( = Match a start parentheses
[^)(]* = Match anything that isn't a parentheses
\) = Match a end parentheses
) = End Group
*\) = Match anything and then a close parens
) = Close non-capturing group
* = Match anything
) = Close capturing group
\) = Match a close parens
/gi = Get all matches, not the first. Be case insensitive.
*/
var fixedCss = css.replace(/url\s*\(((?:[^)(]|\((?:[^)(]+|\([^)(]*\))*\))*)\)/gi, function(fullMatch, origUrl) {
// strip quotes (if they exist)
var unquotedOrigUrl = origUrl
.trim()
.replace(/^"(.*)"$/, function(o, $1){ return $1; })
.replace(/^'(.*)'$/, function(o, $1){ return $1; });
// already a full url? no change
if (/^(#|data:|http:\/\/|https:\/\/|file:\/\/\/|\s*$)/i.test(unquotedOrigUrl)) {
return fullMatch;
}
// convert the url to a full url
var newUrl;
if (unquotedOrigUrl.indexOf("//") === 0) {
//TODO: should we add protocol?
newUrl = unquotedOrigUrl;
} else if (unquotedOrigUrl.indexOf("/") === 0) {
// path should be relative to the base url
newUrl = baseUrl + unquotedOrigUrl; // already starts with '/'
} else {
// path should be relative to current directory
newUrl = currentDir + unquotedOrigUrl.replace(/^\.\//, ""); // Strip leading './'
}
// send back the fixed url(...)
return "url(" + JSON.stringify(newUrl) + ")";
});
// send back the fixed css
return fixedCss;
};