resolve-url.js

/**
@license
Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
*/
import './boot.js';

let CSS_URL_RX = /(url\()([^)]*)(\))/g;
let ABS_URL = /(^\/[^\/])|(^#)|(^[\w-\d]*:)/;
let workingURL;
let resolveDoc;
/**
 * Resolves the given URL against the provided `baseUri'.
 *
 * Note that this function performs no resolution for URLs that start
 * with `/` (absolute URLs) or `#` (hash identifiers).  For general purpose
 * URL resolution, use `window.URL`.
 *
 * @param {string} url Input URL to resolve
 * @param {?string=} baseURI Base URI to resolve the URL against
 * @return {string} resolved URL
 */
export function resolveUrl(url, baseURI) {
  if (url && ABS_URL.test(url)) {
    return url;
  }
  if (url === '//') {
    return url;
  }
  // Lazy feature detection.
  if (workingURL === undefined) {
    workingURL = false;
    try {
      const u = new URL('b', 'http://a');
      u.pathname = 'c%20d';
      workingURL = (u.href === 'http://a/c%20d');
    } catch (e) {
      // silently fail
    }
  }
  if (!baseURI) {
    baseURI = document.baseURI || window.location.href;
  }
  if (workingURL) {
    try {
      return (new URL(url, baseURI)).href;
    } catch (e) {
      // Bad url or baseURI structure. Do not attempt to resolve.
      return url;
    }
  }
  // Fallback to creating an anchor into a disconnected document.
  if (!resolveDoc) {
    resolveDoc = document.implementation.createHTMLDocument('temp');
    resolveDoc.base = resolveDoc.createElement('base');
    resolveDoc.head.appendChild(resolveDoc.base);
    resolveDoc.anchor = resolveDoc.createElement('a');
    resolveDoc.body.appendChild(resolveDoc.anchor);
  }
  resolveDoc.base.href = baseURI;
  resolveDoc.anchor.href = url;
  return resolveDoc.anchor.href || url;

}

/**
 * Resolves any relative URL's in the given CSS text against the provided
 * `ownerDocument`'s `baseURI`.
 *
 * @param {string} cssText CSS text to process
 * @param {string} baseURI Base URI to resolve the URL against
 * @return {string} Processed CSS text with resolved URL's
 */
export function resolveCss(cssText, baseURI) {
  return cssText.replace(CSS_URL_RX, function(m, pre, url, post) {
    return pre + '\'' +
      resolveUrl(url.replace(/["']/g, ''), baseURI) +
      '\'' + post;
  });
}

/**
 * Returns a path from a given `url`. The path includes the trailing
 * `/` from the url.
 *
 * @param {string} url Input URL to transform
 * @return {string} resolved path
 */
export function pathFromUrl(url) {
  return url.substring(0, url.lastIndexOf('/') + 1);
}