feat: Disable next and prev links from global config (#1761)

* core: add lodash deps

* core: disable next and prev links from global config

* doc: add documentation

* core: resolvePageLink function refactoring

* docs: Improve Prev 'Next links' section description

packages/@vuepress/theme-default/components/Page.vue

@@ -62,6 +62,9 @@
 </template>
 
 <script>
+import isString from 'lodash/isString'
+import isNil from 'lodash/isNil'
+
 import { resolvePage, outboundRE, endingSlashRE } from '../util'
 
 export default {
@@ -83,25 +86,11 @@ export default {
     },
 
     prev () {
-      const prev = this.$page.frontmatter.prev
-      if (prev === false) {
-        return
-      } else if (prev) {
-        return resolvePage(this.$site.pages, prev, this.$route.path)
-      } else {
-        return resolvePrev(this.$page, this.sidebarItems)
-      }
+      return resolvePageLink(LINK_TYPES.PREV, this)
     },
 
     next () {
-      const next = this.$page.frontmatter.next
-      if (next === false) {
-        return
-      } else if (next) {
-        return resolvePage(this.$site.pages, next, this.$route.path)
-      } else {
-        return resolveNext(this.$page, this.sidebarItems)
-      }
+      return resolvePageLink(LINK_TYPES.NEXT, this)
     },
 
     editLink () {
@@ -169,6 +158,40 @@ function resolveNext (page, items) {
   return find(page, items, 1)
 }
 
+const LINK_TYPES = {
+  NEXT: {
+    resolveLink: resolveNext,
+    getThemeLinkConfig: ({ nextLinks }) => nextLinks,
+    getPageLinkConfig: ({ frontmatter }) => frontmatter.next
+  },
+  PREV: {
+    resolveLink: resolvePrev,
+    getThemeLinkConfig: ({ prevLinks }) => prevLinks,
+    getPageLinkConfig: ({ frontmatter }) => frontmatter.prev
+  }
+}
+
+function resolvePageLink (linkType, { $themeConfig, $page, $route, $site, sidebarItems }) {
+  const { resolveLink, getThemeLinkConfig, getPageLinkConfig } = linkType
+
+  // Get link config from theme
+  const themeLinkConfig = getThemeLinkConfig($themeConfig)
+
+  // Get link config from current page
+  const pageLinkConfig = getPageLinkConfig($page)
+
+  // Page link config will overwrite global theme link config if defined
+  const link = isNil(pageLinkConfig) ? themeLinkConfig : pageLinkConfig
+
+  if (link === false) {
+    return
+  } else if (isString(link)) {
+    return resolvePage($site.pages, link, $route.path)
+  } else {
+    return resolveLink($page, sidebarItems)
+  }
+}
+
 function find (page, items, offset) {
   const res = []
   flatten(items, res)

packages/@vuepress/theme-default/package.json

@@ -34,6 +34,7 @@
     "@vuepress/plugin-nprogress": "^1.0.3",
     "@vuepress/plugin-search": "^1.0.3",
     "docsearch.js": "^2.5.2",
+    "lodash": "^4.17.15",
     "stylus": "^0.54.5",
     "stylus-loader": "^3.0.2",
     "vuepress-plugin-container": "^2.0.0"

packages/docs/docs/theme/default-theme-config.md

@@ -376,7 +376,7 @@ Note that it’s `off` by default. If given a `string`, it will be displayed as
 
 ## Prev / Next Links
 
-Prev and next links are automatically inferred based on the sidebar order of the active page. You can also explicitly overwrite or disable them using `YAML front matter`:
+Prev and next links are automatically inferred based on the sidebar order of the active page. You can also explicitly overwrite or disable them globally with [theme config](/theme/default-theme-config.html#git-repository-and-edit-links) or on specific pages using `YAML front matter`:
 
 ``` yaml
 ---
@@ -409,17 +409,23 @@ module.exports = {
     docsBranch: 'master',
     // defaults to false, set to true to enable
     editLinks: true,
+    // default value is true. Allows to hide next page links on all pages
+    nextLinks: false,
+    // default value is true. Allows to hide prev page links on all pages
+    prevLinks: false,
     // custom text for edit link. Defaults to "Edit this page"
     editLinkText: 'Help us improve this page!'
   }
 }
 ```
 
-You can also hide the edit link on a specific page via `YAML front matter`:
+You can overwrite the following properties on specific pages via `YAML front matter`:
 
 ``` yaml
 ---
-editLink: false
+editLink: false # Will overwrite 'editLinks' from themeConfig
+prev: true # Will overwrite 'prevLinks' property from themeConfig
+next: ./my-next-page # Will overwrite 'nextLinks' property from themeConfig
 ---
 ```
 

yarn.lock

@@ -7316,7 +7316,7 @@ lodash.uniq@^4.5.0:
   version "4.5.0"
   resolved "https://registry.yarnpkg.com/lodash.uniq/-/lodash.uniq-4.5.0.tgz#d0225373aeb652adc1bc82e4945339a842754773"
 
-lodash@^4.0.0, lodash@^4.11.2, lodash@^4.17.12:
+lodash@^4.0.0, lodash@^4.11.2, lodash@^4.17.12, lodash@^4.17.15:
   version "4.17.15"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.15.tgz#b447f6670a0455bbfeedd11392eff330ea097548"