解析相对 css 文件的图片路径

resolve-to.js

  /**
   * 解析相对 css 文件的图片路径
   *
   * @param baseurl
   * @returns {undefined}
   */
  function resolveTo (baseurl) {
    return function (relativePath) {
      // 绝对路径
      if (relativePath[0] === '/') {
        return location.origin + relativePath[0]
      } else if (relativePath.startsWith('data:')) {
        return relativePath
      }
      let url = new URL(baseurl)
      let origin = url.origin
      let segs = `${origin}${url.pathname}`.split('/')
      segs.pop() // 去掉文件名
      let relativeSegs = relativePath.split('/')
      let seg
      do {
        seg = relativeSegs[0]
        if (seg === '.') {
          relativeSegs.shift()
        } else if (seg === '..') {
          relativeSegs.shift()
          segs.pop()
        } else {
          break;
        }
      } while (seg)
      return segs.concat(relativeSegs).join('/')
    }
  }