first commit

static/book.js

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+function initToggleMenu() {
+  var $menu = document.querySelector(".menu");
+  var $menuIcon = document.querySelector(".menu-icon");
+  var $page = document.querySelector(".page");
+  $menuIcon.addEventListener("click", function() {
+    $menu.classList.toggle("menu-hidden");
+    $page.classList.toggle("page-without-menu");
+  });
+}
+
+function debounce(func, wait) {
+  var timeout;
+
+  return function () {
+    var context = this;
+    var args = arguments;
+    clearTimeout(timeout);
+
+    timeout = setTimeout(function () {
+      timeout = null;
+      func.apply(context, args);
+    }, wait);
+  };
+}
+
+// Taken from mdbook
+// The strategy is as follows:
+// First, assign a value to each word in the document:
+//  Words that correspond to search terms (stemmer aware): 40
+//  Normal words: 2
+//  First word in a sentence: 8
+// Then use a sliding window with a constant number of words and count the
+// sum of the values of the words within the window. Then use the window that got the
+// maximum sum. If there are multiple maximas, then get the last one.
+// Enclose the terms in <b>.
+function makeTeaser(body, terms) {
+  var TERM_WEIGHT = 40;
+  var NORMAL_WORD_WEIGHT = 2;
+  var FIRST_WORD_WEIGHT = 8;
+  var TEASER_MAX_WORDS = 30;
+
+  var stemmedTerms = terms.map(function (w) {
+    return elasticlunr.stemmer(w.toLowerCase());
+  });
+  var termFound = false;
+  var index = 0;
+  var weighted = []; // contains elements of ["word", weight, index_in_document]
+
+  // split in sentences, then words
+  var sentences = body.toLowerCase().split(". ");
+
+  for (var i in sentences) {
+    var words = sentences[i].split(" ");
+    var value = FIRST_WORD_WEIGHT;
+
+    for (var j in words) {
+      var word = words[j];
+
+      if (word.length > 0) {
+        for (var k in stemmedTerms) {
+          if (elasticlunr.stemmer(word).startsWith(stemmedTerms[k])) {
+            value = TERM_WEIGHT;
+            termFound = true;
+          }
+        }
+        weighted.push([word, value, index]);
+        value = NORMAL_WORD_WEIGHT;
+      }
+
+      index += word.length;
+      index += 1;  // ' ' or '.' if last word in sentence
+    }
+
+    index += 1;  // because we split at a two-char boundary '. '
+  }
+
+  if (weighted.length === 0) {
+    return body;
+  }
+
+  var windowWeights = [];
+  var windowSize = Math.min(weighted.length, TEASER_MAX_WORDS);
+  // We add a window with all the weights first
+  var curSum = 0;
+  for (var i = 0; i < windowSize; i++) {
+    curSum += weighted[i][1];
+  }
+  windowWeights.push(curSum);
+
+  for (var i = 0; i < weighted.length - windowSize; i++) {
+    curSum -= weighted[i][1];
+    curSum += weighted[i + windowSize][1];
+    windowWeights.push(curSum);
+  }
+
+  // If we didn't find the term, just pick the first window
+  var maxSumIndex = 0;
+  if (termFound) {
+    var maxFound = 0;
+    // backwards
+    for (var i = windowWeights.length - 1; i >= 0; i--) {
+      if (windowWeights[i] > maxFound) {
+        maxFound = windowWeights[i];
+        maxSumIndex = i;
+      }
+    }
+  }
+
+  var teaser = [];
+  var startIndex = weighted[maxSumIndex][2];
+  for (var i = maxSumIndex; i < maxSumIndex + windowSize; i++) {
+    var word = weighted[i];
+    if (startIndex < word[2]) {
+      // missing text from index to start of `word`
+      teaser.push(body.substring(startIndex, word[2]));
+      startIndex = word[2];
+    }
+
+    // add <em/> around search terms
+    if (word[1] === TERM_WEIGHT) {
+      teaser.push("<b>");
+    }
+    startIndex = word[2] + word[0].length;
+    teaser.push(body.substring(word[2], startIndex));
+
+    if (word[1] === TERM_WEIGHT) {
+      teaser.push("</b>");
+    }
+  }
+  teaser.push("…");
+  return teaser.join("");
+}
+
+function formatSearchResultItem(item, terms) {
+  var li = document.createElement("li");
+  li.classList.add("search-results__item");
+  li.innerHTML = `<a href="${item.ref}">${item.doc.title}</a>`;
+  li.innerHTML += `<div class="search-results__teaser">${makeTeaser(item.doc.body, terms)}</div>`;
+  return li;
+}
+
+// Go from the book view to the search view
+function toggleSearchMode() {
+  var $bookContent = document.querySelector(".book-content");
+  var $searchContainer = document.querySelector(".search-container");
+  if ($searchContainer.classList.contains("search-container--is-visible")) {
+    $searchContainer.classList.remove("search-container--is-visible");
+    document.body.classList.remove("search-mode");
+    $bookContent.style.display = "block";
+  } else {
+    $searchContainer.classList.add("search-container--is-visible");
+    document.body.classList.add("search-mode");
+    $bookContent.style.display = "none";
+    document.getElementById("search").focus();
+  }
+}
+
+function initSearch() {
+  var $searchInput = document.getElementById("search");
+  if (!$searchInput) {
+    return;
+  }
+  var $searchIcon = document.querySelector(".search-icon");
+  $searchIcon.addEventListener("click", toggleSearchMode);
+
+  var $searchResults = document.querySelector(".search-results");
+  var $searchResultsHeader = document.querySelector(".search-results__header");
+  var $searchResultsItems = document.querySelector(".search-results__items");
+  var MAX_ITEMS = 10;
+
+  var options = {
+    bool: "AND",
+    fields: {
+      title: {boost: 2},
+      body: {boost: 1},
+    }
+  };
+  var currentTerm = "";
+  var index = elasticlunr.Index.load(window.searchIndex);
+
+  $searchInput.addEventListener("keyup", debounce(function() {
+    var term = $searchInput.value.trim();
+    if (term === currentTerm || !index) {
+      return;
+    }
+    $searchResults.style.display = term === "" ? "none" : "block";
+    $searchResultsItems.innerHTML = "";
+    if (term === "") {
+      return;
+    }
+
+    var results = index.search(term, options).filter(function (r) {
+      return r.doc.body !== "";
+    });
+    if (results.length === 0) {
+      $searchResultsHeader.innerText = `No search results for '${term}'.`;
+      return;
+    }
+
+    currentTerm = term;
+      $searchResultsHeader.innerText = `${results.length} search results for '${term}':`;
+    for (var i = 0; i < Math.min(results.length, MAX_ITEMS); i++) {
+      if (!results[i].doc.body) {
+        continue;
+      }
+      // var item = document.createElement("li");
+      // item.innerHTML = formatSearchResultItem(results[i], term.split(" "));
+      console.log(results[i]);
+      $searchResultsItems.appendChild(formatSearchResultItem(results[i], term.split(" ")));
+    }
+  }, 150));
+}
+
+if (document.readyState === "complete" ||
+    (document.readyState !== "loading" && !document.documentElement.doScroll)
+) {
+  initToggleMenu();
+} else {
+  document.addEventListener("DOMContentLoaded", function () {
+    initToggleMenu();
+    initSearch();
+  });
+}