Function complete

background_scripts/completion/search_wrapper.js:95–165

(searchUrl, queryTerms)

//    engine's URL. This is only used as a key for determining the relevant completion engine.
//  - queryTerms are the query terms.
export async function complete(searchUrl, queryTerms) {
  const query = queryTerms.join(" ").toLowerCase();

  // We don't complete queries which are too short: the results are usually useless.
  if (query.length < 4) return [];

  // We don't complete regular URLs or Javascript URLs.
  if (queryTerms.length == 1 && await UrlUtils.isUrl(query)) return [];
  if (UrlUtils.hasJavascriptProtocol(query)) return [];

  const engine = lookupEngine(searchUrl);
  if (!engine) return [];

  const completionCacheKey = JSON.stringify([searchUrl, queryTerms]);
  if (completionCache.has(completionCacheKey)) {
    if (debug) console.log("hit", completionCacheKey);
    return completionCache.get(completionCacheKey);
  }

  const createTimeoutPromise = (ms) => {
    return new Promise((resolve) => {
      setTimeout(() => {
        resolve();
      }, ms);
    });
  };

  requestId++;
  const lastRequestId = requestId;

  // We delay sending a completion request in case the user is still typing.
  await createTimeoutPromise(DELAY);

  // If the user has issued a new query while we were waiting, then this query is old; abort it.
  if (lastRequestId != requestId) return [];

  const engineWrapper = new EnginePrefixWrapper(searchUrl, engine);
  const url = engineWrapper.getUrl(queryTerms);

  if (debug) console.log("GET", url);
  const responseText = await get(url);

  // Parsing the response may fail if we receive an unexpectedly-formatted response. In all cases,
  // we fall back to the catch clause, below. Therefore, we "fail safe" in the case of incorrect
  // or out-of-date completion engine implementations.
  let suggestions = [];
  let isError = responseText == null;
  if (!isError) {
    try {
      suggestions = engineWrapper.parse(responseText)
        // Make all suggestions lower case. It looks odd when suggestions from one
        // completion engine are upper case, and those from another are lower case.
        .map((s) => s.toLowerCase())
        // Filter out the query itself. It's not adding anything.
        .filter((s) => s !== query);
    } catch (error) {
      if (debug) console.log("error:", error);
      isError = true;