added search input with simple search result preview

1 files changed, 111 insertions, 0 deletions

diff --git a/static/search.js b/static/search.js
new file mode 100644
index 0000000..02f1814
--- /dev/null
+++ b/static/search.js
@@ -0,0 +1,111 @@
+// Copyright (c) 2021 Johannes Stoelp
+// file: search.js
+
+const formatResultPreview = (body, terms) => {
+    let body_idx = 0;
+
+    // Collect indexes into `body` that match any term.
+    let matches = body.toLowerCase().split(" ").map(word => {
+        let idx = body_idx;
+
+        // Update global index into body.
+        body_idx += word.length + 1 /* for the ' ' split char */;
+
+        if (terms.some(term => { return word.startsWith(term); })) {
+            return { idx : idx, end : idx + word.length };
+        } else {
+            return null;
+        }
+    }).filter(match => { return match !== null; });
+
+    // Format preview, by making each term bold and adding a short slice
+    // following after the term.
+    let preview = [];
+    matches.forEach(match => {
+        let end = Math.min(match.end + 40, body.length - 1);
+        preview.push(`<b>${body.substring(match.idx, match.end)}</b>`
+                   + body.substring(match.end, end)
+                   + "...");
+    });
+
+    return preview.join(" ");
+}
+
+const formatResult = (result, terms) => {
+    return "<div>"
+         + `<a href="${result.ref}">${result.doc.title}</a>`
+         + `<div>${formatResultPreview(result.doc.body, terms)}</div>`
+         + "</div>";
+}
+
+const evaluteSearch = (ctx) => {
+    let term = ctx.input.value.trim();
+
+    // Nothing todo if current search term is the same as last one.
+    if (term === ctx.last_search) {
+        return;
+    }
+
+    // Empty search term, show list of blog pages again.
+    if (term === "") {
+        ctx.pages.style.display = "block";
+        ctx.results.style.display = "none";
+        return;
+    }
+
+    // Search term entered, show result list and hide list with blog posts.
+    ctx.pages.style.display = "none";
+    ctx.results.style.display = "block";
+
+    // Perform actual search.
+    let results = ctx.search_index.search(term, {
+        bool: "AND",
+        expand: true, // Also match if words starts with search query.
+        fields: {
+            title: {boost: 2},
+            body : {boost: 1},
+        }
+    });
+
+    if (results.length !== 0) {
+        // Update last search term.
+        ctx.last_search = term;
+
+        // Reset HTML of results items (previous search results).
+        ctx.results_items.innerHTML = "";
+        // Generate HTML for search results.
+        results.forEach(result => {
+            let item = document.createElement("li");
+            item.innerHTML = formatResult(result, term.split(" "));
+            ctx.results_items.appendChild(item);
+        });
+    }
+};
+
+const debounce = (func, wait) => {
+    let timeout = null;
+    return () => {
+        clearTimeout(timeout);
+        timeout = setTimeout(func , wait);
+    };
+}
+
+window.onload = () => {
+    let ctx = new class {
+        constructor() {
+            // Get HTML DOM elements.
+            this.input = document.getElementById("search");
+            this.results = document.getElementById("search-results");
+            this.results_items = document.getElementById("search-results-items");
+            this.pages = document.getElementById("pages");
+            // Load search index.
+            this.search_index = elasticlunr.Index.load(window.searchIndex);
+            // Last search term.
+            this.last_search = "";
+        }
+    };
+
+    if (ctx.search_index) {
+        ctx.input.onkeyup = debounce(() => { evaluteSearch(ctx); }, 200);
+    }
+}