feat: implement scrollspy

gatsby-config.js

@@ -73,12 +73,6 @@ module.exports = {
       },
     },
     `gatsby-transformer-sharp`,
-    {
-      resolve: "gatsby-plugin-anchor-links",
-      options: {
-        offset: -100,
-      },
-    },
     `gatsby-plugin-react-svg`,
     `gatsby-plugin-remove-trailing-slashes`,
     `gatsby-plugin-sharp`,

package-lock.json

@@ -3753,6 +3753,15 @@
         "@types/react": "*"
       }
     },
+    "@types/react-scrollspy": {
+      "version": "3.3.2",
+      "resolved": "https://registry.npmjs.org/@types/react-scrollspy/-/react-scrollspy-3.3.2.tgz",
+      "integrity": "sha512-nbCB4wg2AhsFWKZ0LnMqGZWWC+6fNOC4USCzvBC++YST7tLMGvQKLVdWCQHec5/HzSlrSD4UfnYYVcuSYIhvmg==",
+      "dev": true,
+      "requires": {
+        "@types/react": "*"
+      }
+    },
     "@types/rimraf": {
       "version": "2.0.4",
       "resolved": "https://registry.npmjs.org/@types/rimraf/-/rimraf-2.0.4.tgz",
@@ -10151,14 +10160,6 @@
         }
       }
     },
-    "gatsby-plugin-anchor-links": {
-      "version": "1.1.1",
-      "resolved": "https://registry.npmjs.org/gatsby-plugin-anchor-links/-/gatsby-plugin-anchor-links-1.1.1.tgz",
-      "integrity": "sha512-mgSHUAEa7RRWD/lcmJVUWD9mIT14EIJvMPcxJ1W2Ev+rNuqBBpk1j4vDWy1uxas+qusi0vrtZ4HdU7mse12qDw==",
-      "requires": {
-        "scroll-to-element": "^2.0.3"
-      }
-    },
     "gatsby-plugin-google-fonts": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/gatsby-plugin-google-fonts/-/gatsby-plugin-google-fonts-1.0.1.tgz",
@@ -17348,14 +17349,6 @@
       "resolved": "https://registry.npmjs.org/querystringify/-/querystringify-2.1.1.tgz",
       "integrity": "sha512-w7fLxIRCRT7U8Qu53jQnJyPkYZIaR4n5151KMfcJlO/A9397Wxb1amJvROTK6TOnp7PfoAmg/qXiNHI+08jRfA=="
     },
-    "raf": {
-      "version": "3.4.1",
-      "resolved": "https://registry.npmjs.org/raf/-/raf-3.4.1.tgz",
-      "integrity": "sha512-Sq4CW4QhwOHE8ucn6J34MqtZCeWFP2aQSmrlroYgqAV1PjStIhJXxYuTgUIfkEk7zTLjmIjLmU5q+fbD1NnOJA==",
-      "requires": {
-        "performance-now": "^2.1.0"
-      }
-    },
     "ramda": {
       "version": "0.27.0",
       "resolved": "https://registry.npmjs.org/ramda/-/ramda-0.27.0.tgz",
@@ -17734,6 +17727,16 @@
       "resolved": "https://registry.npmjs.org/react-refresh/-/react-refresh-0.7.2.tgz",
       "integrity": "sha512-u5l7fhAJXecWUJzVxzMRU2Zvw8m4QmDNHlTrT5uo3KBlYBhmChd7syAakBoay1yIiVhx/8Fi7a6v6kQZfsw81Q=="
     },
+    "react-scrollspy": {
+      "version": "3.4.2",
+      "resolved": "https://registry.npmjs.org/react-scrollspy/-/react-scrollspy-3.4.2.tgz",
+      "integrity": "sha512-mFev6IBPPGdn0WsAiS0eCoHGUUet0ZRZUHHUw3qLcsvsQZPlubik0N9cf8CcgIbdVzNd04K9L9A0inHhPt7drw==",
+      "requires": {
+        "babel-runtime": "^6.26.0",
+        "classnames": "^2.2.5",
+        "prop-types": "^15.5.10"
+      }
+    },
     "react-side-effect": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/react-side-effect/-/react-side-effect-2.1.0.tgz",
@@ -18716,14 +18719,6 @@
         "invariant": "^2.2.4"
       }
     },
-    "scroll-to-element": {
-      "version": "2.0.3",
-      "resolved": "https://registry.npmjs.org/scroll-to-element/-/scroll-to-element-2.0.3.tgz",
-      "integrity": "sha512-5herPcm9jMfQgRwu94lH5mei+2YhipR4RQ2nAvnBxJb2tG+P7O0ctOKAaAZBXbBejnn+MImh3wrAUA5EcLnjEQ==",
-      "requires": {
-        "raf": "^3.4.0"
-      }
-    },
     "scuid": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/scuid/-/scuid-1.1.0.tgz",

package.json

@@ -33,7 +33,6 @@
     "@reach/router": "^1.3.3",
     "classnames": "^2.2.6",
     "gatsby": "^2.22.11",
-    "gatsby-plugin-anchor-links": "^1.1.1",
     "gatsby-plugin-google-fonts": "^1.0.1",
     "gatsby-plugin-layout": "^1.3.2",
     "gatsby-plugin-manifest": "^2.4.9",
@@ -57,6 +56,7 @@
     "react-highlight": "^0.12.0",
     "react-particles-js": "^3.2.1",
     "react-perfect-scrollbar": "^1.5.8",
+    "react-scrollspy": "^3.4.2",
     "styled-components": "^5.1.1",
     "typescript": "^3.9.3"
   },
@@ -72,6 +72,7 @@
     "@types/react": "^16.9.35",
     "@types/react-dom": "^16.9.8",
     "@types/react-helmet": "^6.0.0",
+    "@types/react-scrollspy": "^3.3.2",
     "@types/styled-components": "^5.1.0",
     "babel-plugin-polished": "^1.1.0",
     "babel-plugin-styled-components": "^1.10.7",

src/components/PageSidebarLink/index.tsx

@@ -16,7 +16,7 @@ export const PageSidebarLink: FC<IPageSidebarLinkProps> = ({
   type = "internal",
 }) => {
   if (type === "anchor") {
-    return <SC.Anchor to={href}>{text}</SC.Anchor>
+    return <SC.Anchor href={href}>{text}</SC.Anchor>
   }
 
   if (type === "external") {

src/components/PageSidebarLink/styles.tsx

@@ -1,4 +1,3 @@
-import { AnchorLink } from "gatsby-plugin-anchor-links"
 import styled, { css } from "styled-components"
 import { Link } from "gatsby"
 
@@ -13,7 +12,7 @@ const extraLink = css`
   }
 `
 
-export const Anchor = styled(AnchorLink)`
+export const Anchor = styled.a`
   ${extraLink};
 `
 

src/components/Toc/index.tsx

@@ -1,4 +1,6 @@
+import cx from "classnames"
 import React, { FC } from "react"
+import Scrollspy from "react-scrollspy"
 import { PageSidebarLink } from "../PageSidebarLink"
 import { ITocItem } from "../../types"
 import * as SC from "./styles"
@@ -24,31 +26,40 @@ function extractTitle(title: string): ITitle {
 }
 
 export const Toc: FC<ITocProps> = ({ header, items }) => {
-  const windowGlobal = typeof window !== "undefined" && window
+  const [scrollSpyCache, setScrollSpyCache] = React.useState<string>()
 
-  // window is not available on build
-  if (!windowGlobal) {
-    return null
-  }
-
-  const { pathname } = windowGlobal.location
   return (
     <SC.TocWrapper>
       {header}
-      {items.map((item) => {
-        const { prefix, title } = extractTitle(item.title)
+      <Scrollspy
+        items={items.map((item) => item.link.substring(1))}
+        currentClassName="scrollspy-current"
+        scrolledPastClassName="scrollspy-past"
+        componentTag={SC.ScrollspyWrapper}
+        onUpdate={(updatedElement: HTMLDivElement) => {
+          // @ts-ignore
+          const id = updatedElement?.id
+          if (id) {
+            setScrollSpyCache(id)
+          }
+        }}
+      >
+        {items.map((item) => {
+          const { prefix, title } = extractTitle(item.title)
 
-        return (
-          <SC.TocItem key={item.link} className={`depth-${item.depth}`}>
-            {prefix}
-            <PageSidebarLink
-              href={`${pathname}${item.link}`}
-              text={title}
-              type="anchor"
-            />
-          </SC.TocItem>
-        )
-      })}
+          return (
+            <SC.TocItem
+              key={item.link}
+              className={cx(`depth-${item.depth}`, {
+                "scrollspy-cached": scrollSpyCache === item.link.substring(1),
+              })}
+            >
+              {prefix}
+              <PageSidebarLink href={item.link} text={title} type="anchor" />
+            </SC.TocItem>
+          )
+        })}
+      </Scrollspy>
     </SC.TocWrapper>
   )
 }

src/components/Toc/styles.tsx

@@ -5,15 +5,34 @@ export const TocWrapper = styled.div`
   flex-direction: column;
 `
 
+export const ScrollspyWrapper = styled.div`
+  display: flex;
+  flex-direction: column;
+`
+
 export const TocItem = styled.div`
   display: inline-block;
 
-  &.depth-3 {
-    margin-left: 8px;
+  &.scrollspy-current,
+  &.scrollspy-cached {
+    position: relative;
+    text-shadow: 0 0 0.65px ${(props) => props.theme.main.foreground},
+      0 0 0.65px ${(props) => props.theme.main.foreground};
+
+    &::after {
+      position: absolute;
+      top: 0;
+      left: -16px;
+      content: "";
+      display: block;
+      background: ${(props) => props.theme.main.foreground};
+      width: 2px;
+      height: 100%;
+    }
   }
 
-  &.depth-2 + &.depth-2,
-  &.depth-3 + &.depth-2 {
-    margin-top: 8px;
+  &.depth-2,
+  &.depth-3 {
+    padding: 4px 0;
   }
 `