feat: allows relative path, fixed docsifyjs#590

Author: Sylvain Brocard

docs/configuration.md

@@ -150,6 +150,46 @@ window.$docsify = {
 };
 ```
 
+## relativePath
+
+- Type: `Boolean`
+- Default: `false`
+
+If **true** links are relative to the current context.
+
+For example, the directory structure is as follows:
+
+```text
+.
+└── docs
+    ├── README.md
+    ├── guide.md
+    └── zh-cn
+        ├── README.md
+        ├── guide.md
+        └── config
+            └── example.md
+```
+
+With relative path **enabled** and current URL `http://domain.com/zh-cn/README`, given links will resolve to:
+
+```text
+guide.md              => http://domain.com/zh-cn/guide
+config/example.md     => http://domain.com/zh-cn/config/example
+../README.md          => http://domain.com/README
+/README.md            => http://domain.com/README
+```
+
+```js
+window.$docsify = {
+  // Relative path enabled
+  relativePath: true,
+
+  // Relative path disabled (default value)
+  relativePath: false
+};
+```
+
 ## coverpage
 
 - Type: `Boolean|String|String[]|Object`

src/core/config.js

@@ -25,7 +25,8 @@ export default function () {
       formatUpdated: '',
       externalLinkTarget: '_blank',
       routerMode: 'hash',
-      noCompileLinks: []
+      noCompileLinks: [],
+      relativePath: false
     },
     window.$docsify
   )

src/core/router/history/base.js

@@ -3,7 +3,8 @@ import {
   isAbsolutePath,
   stringifyQuery,
   cleanPath,
-  replaceSlug
+  replaceSlug,
+  resolvePath
 } from '../util'
 import {noop, merge} from '../../util/core'
 
@@ -76,6 +77,10 @@ export class History {
         (idIndex > 0 ? currentRoute.substr(0, idIndex) : currentRoute) + path
     }
 
+    if (this.config.relativePath && !path.startsWith('/')) {
+      const currentDir = currentRoute.substr(0, currentRoute.lastIndexOf('/') + 1)
+      return cleanPath(resolvePath(currentDir + path))
+    }
     return cleanPath('/' + path)
   }
 }

src/core/router/util.js

@@ -53,6 +53,20 @@ export const cleanPath = cached(path => {
   return path.replace(/^\/+/, '/').replace(/([^:])\/{2,}/g, '$1/')
 })
 
+export const resolvePath = cached(path => {
+  const segments = path.replace(/^\//, '').split('/')
+  let resolved = []
+  for (let i = 0, len = segments.length; i < len; i++) {
+    const segment = segments[i]
+    if (segment === '..') {
+      resolved.pop()
+    } else if (segment !== '.') {
+      resolved.push(segment)
+    }
+  }
+  return '/' + resolved.join('/')
+})
+
 export function getPath(...args) {
   return cleanPath(args.join('/'))
 }