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 . 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 around search terms if (word[1] === TERM_WEIGHT) { teaser.push(""); } startIndex = word[2] + word[0].length; teaser.push(body.substring(word[2], startIndex)); if (word[1] === TERM_WEIGHT) { teaser.push(""); } } teaser.push("…"); return teaser.join(""); } function formatSearchResultItem(item, terms) { return '
' + `

${item.doc.title}

` + `

${makeTeaser(item.doc.body, terms)}

` + '
'; } function initSearch() { var $searchInput = document.getElementById("search"); var $searchResults = document.querySelector(".search-results"); var $searchResultsItems = document.querySelector(".search-results__items"); var MAX_ITEMS = 20; 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 = ""; currentTerm = term; if (term === "") { return; } var results = index.search(term, options); if (results.length === 0) { $searchResults.style.display = "none"; return; } for (var i = 0; i < Math.min(results.length, MAX_ITEMS); i++) { var item = document.createElement("li"); item.innerHTML = formatSearchResultItem(results[i], term.split(" ")); $searchResultsItems.appendChild(item); } }, 150)); } if (document.readyState === "complete" || (document.readyState !== "loading" && !document.documentElement.doScroll) ) { initSearch(); } else { document.addEventListener("DOMContentLoaded", initSearch); }