commit 622d2a008106c4b3751b55330658f6295088977f · dunkirk.sh/zera

+149

static/js/404-matcher.js

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       // Taken from Vale's 404 Guesser

     

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       // https://vale.rocks/assets/scripts/404-guesser.js

     

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       // which was based on Gwern's 404 Error Page URL Suggester

     

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       // https://gwern.net/static/js/404-guesser.js

     

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       class URLSuggester {

     

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         constructor() {

     

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           this.maxDistance = 8;

     

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           this.urls = [];

     

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         }

     

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         async initialize() {

     

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           try {

     

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             const sitemapText = await this.fetchSitemap();

     

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             if (sitemapText) {

     

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               this.urls = this.parseUrls(sitemapText);

     

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               const currentPath = window.location.pathname;

     

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               if (!currentPath.endsWith("/404")) {

     

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                 const suggestions = this.findSimilarUrls(currentPath);

     

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                 this.injectSuggestions(currentPath, suggestions);

     

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               }

     

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             }

     

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           } catch (error) {

     

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             console.error("Error initializing URL suggester:", error);

     

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           }

     

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         }

     

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         async fetchSitemap() {

     

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           try {

     

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             const response = await fetch("/sitemap.xml");

     

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             return await response.text();

     

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           } catch (error) {

     

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             console.error("Error fetching sitemap:", error);

     

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             return null;

     

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           }

     

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         }

     

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         parseUrls(sitemapText) {

     

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           const parser = new DOMParser();

     

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           const xmlDoc = parser.parseFromString(sitemapText, "text/xml");

     

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           const urlNodes = xmlDoc.getElementsByTagName("url");

     

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           return Array.from(urlNodes).map(

     

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             (node) =>

     

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               new URL(node.getElementsByTagName("loc")[0].textContent).pathname,

     

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           );

     

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         }

     

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         boundedLevenshteinDistance(a, b, maxDistance) {

     

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           if (Math.abs(a.length - b.length) > maxDistance) return maxDistance + 1;

     

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           const matrix = Array(b.length + 1)

     

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             .fill(null)

     

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             .map((_, i) => [i]);

     

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           for (let j = 1; j <= a.length; j++) {

     

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             matrix[0][j] = j;

     

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           }

     

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           for (let i = 1; i <= b.length; i++) {

     

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             let minDistance = maxDistance + 1;

     

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             for (let j = 1; j <= a.length; j++) {

     

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               if (b.charAt(i - 1) === a.charAt(j - 1)) {

     

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                 matrix[i][j] = matrix[i - 1][j - 1];

     

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               } else {

     

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                 matrix[i][j] = Math.min(

     

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                   matrix[i - 1][j - 1] + 1,

     

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                   matrix[i][j - 1] + 1,

     

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                   matrix[i - 1][j] + 1,

     

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                 );

     

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               }

     

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               minDistance = Math.min(minDistance, matrix[i][j]);

     

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             }

     

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             if (minDistance > maxDistance) {

     

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               return maxDistance + 1;

     

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             }

     

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           }

     

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           return matrix[b.length][a.length];

     

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         }

     

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         findSimilarUrls(targetUrl) {

     

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           const targetPath = new URL(targetUrl, location.origin).pathname;

     

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           if (targetPath.startsWith("/posts/")) {

     

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             const exactMatch = this.urls.find((url) => url === targetPath);

     

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             if (exactMatch) {

     

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               return [location.origin + exactMatch];

     

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             }

     

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           }

     

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           const potentialMatches = this.urls.filter(

     

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             (url) =>

     

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               Math.abs(url.length - targetPath.length) <= this.maxDistance &&

     

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               !url.endsWith("/404.html"),

     

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           );

     

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           const similarUrls = potentialMatches

     

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             .map((url) => ({

     

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               url,

     

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               distance: this.boundedLevenshteinDistance(

     

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                 url,

     

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                 targetPath,

     

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                 this.maxDistance,

     

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               ),

     

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             }))

     

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             .filter((item) => item.distance <= this.maxDistance)

     

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             .sort((a, b) => a.distance - b.distance);

     

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           const seenUrls = new Set();

     

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           const uniqueSimilarUrls = similarUrls

     

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             .filter((item) => {

     

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               if (seenUrls.has(item.url)) return false;

     

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               seenUrls.add(item.url);

     

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               return true;

     

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             })

     

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             .slice(0, 10);

     

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           return uniqueSimilarUrls.map((item) => location.origin + item.url);

     

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         }

     

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         injectSuggestions(currentPath, suggestions) {

     

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           const app = document.querySelector("#suggestions");

     

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           if (!app) return;

     

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           if (suggestions.length > 0) {

     

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             const p = document.createElement("p");

     

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             p.innerHTML = "I did however find some URLs that might be relevant?";

     

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             app.appendChild(p);

     

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             for (const url of suggestions) {

     

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               const a = document.createElement("a");

     

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               const cleanUrl = url.replace(/\.html$/, "");

     

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               a.href = cleanUrl;

     

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               a.textContent = cleanUrl;

     

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               app.appendChild(a);

     

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             }

     

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             const endText = document.createElement("p");

     

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             app.appendChild(endText);

     

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           } else {

     

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             const p = document.createElement("p");

     

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             p.innerHTML = `Couldn't find any URLs similar to <code>${currentPath}</code>. I guess it's time to find something new`;

     

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             app.appendChild(p);

     

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           }

     

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           app.className = "url-suggestions";

     

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         }

     

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       }

     

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       document.addEventListener("DOMContentLoaded", () => {

     

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         new URLSuggester().initialize();

     

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       });

+9 -3

templates/404.html

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       {% extends "base.html" %} {% block content %}

     

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       <div

     

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           id="suggestions"

     

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           style="

     

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               display: flex;

     

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               flex-direction: column;

     
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           "

     

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       >

     

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           <p><strong>I think you stumbled on something non existent :)</strong></p>

     

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           <p><i id="redirect">Redirecting you back home in 5</i></p>

     

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       </div>

     

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       <script>

     

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       {% set jsHash = get_hash(path="js/404-matcher.js", sha_type=256, base64=true) %}

     

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       <script

     

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           src="{{ get_url(path='js/404-matcher.js?' ~ jsHash, trailing_slash=false) | safe }}"

     

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           defer

     

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       ></script>

     

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       <!-- <script>

     

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           const link = document.getElementById("redirect");

     

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           // count down to redirect

     
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                   window.location.href = "/";

     

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               }

     

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           }, 1000);

     

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       </script>

     

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       </script> -->

     

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       {% endblock content %}