submit-social-housing-lettings-and-sales-data/app/frontend/modules/search.js

const addWeightWithBoost = (option, query) => {
  option.weight = calculateWeight(option.clean, query) * option.clean.boost;

  return option;
};

const clean = (text) =>
  text
    .trim()
    .replace(/['’]/g, "")
    .replace(/[.,"/#!$%^&*;:{}=\-_`~()]/g, " ")
    .toLowerCase();

const cleanseOption = (option) => {
  const synonyms = (option.synonyms || []).map(clean);

  option.clean = {
    name: clean(option.name),
    nameWithoutStopWords: removeStopWords(option.name),
    synonyms: synonyms,
    synonymsWithoutStopWords: synonyms.map(removeStopWords),
    boost: option.boost || 1,
  };

  return option;
};

const hasWeight = (option) => option.weight > 0;

const byWeightThenAlphabetically = (a, b) => {
  if (a.weight > b.weight) return -1;
  if (a.weight < b.weight) return 1;
  if (a.name < b.name) return -1;
  if (a.name > b.name) return 1;

  return 0;
};

const optionName = (option) => option.name;
const exactMatch = (word, query) => word === query;

const startsWithRegExp = (query) => new RegExp("\\b" + query, "i");
const startsWith = (word, query) => word.search(startsWithRegExp(query)) === 0;

const wordsStartsWithQuery = (word, regExps) =>
  regExps.every((regExp) => word.search(regExp) >= 0);

const anyMatch = (words, query, evaluatorFunc) =>
  words.some((word) => evaluatorFunc(word, query));
const synonymsExactMatch = (synonyms, query) =>
  anyMatch(synonyms, query, exactMatch);
const synonymsStartsWith = (synonyms, query) =>
  anyMatch(synonyms, query, startsWith);

const wordInSynonymStartsWithQuery = (synonyms, startsWithQueryWordsRegexes) =>
  anyMatch(synonyms, startsWithQueryWordsRegexes, wordsStartsWithQuery);

const calculateWeight = (
  { name, synonyms, nameWithoutStopWords, synonymsWithoutStopWords },
  query
) => {
  const queryWithoutStopWords = removeStopWords(query);

  if (exactMatch(name, query)) return 100;
  if (exactMatch(nameWithoutStopWords, queryWithoutStopWords)) return 95;

  if (synonymsExactMatch(synonyms, query)) return 75;
  if (synonymsExactMatch(synonymsWithoutStopWords, queryWithoutStopWords))
    return 70;

  if (startsWith(name, query)) return 60;
  if (startsWith(nameWithoutStopWords, queryWithoutStopWords)) return 55;

  if (synonymsStartsWith(synonyms, query)) return 50;
  if (synonymsStartsWith(synonyms, queryWithoutStopWords)) return 40;

  const startsWithRegExps = queryWithoutStopWords
    .split(/\s+/)
    .map(startsWithRegExp);

  if (wordsStartsWithQuery(nameWithoutStopWords, startsWithRegExps)) return 25;
  if (wordInSynonymStartsWithQuery(synonymsWithoutStopWords, startsWithRegExps))
    return 10;

  return 0;
};

const stopWords = ["the", "of", "in", "and", "at", "&"];

const removeStopWords = (text) => {
  const isAllStopWords = text
    .trim()
    .split(" ")
    .every((word) => stopWords.includes(word));

  if (isAllStopWords) {
    return text;
  }

  const regex = new RegExp(
    stopWords.map((word) => `(\\s+)?${word}(\\s+)?`).join("|"),
    "gi"
  );
  return text.replace(regex, " ").trim();
};

export const sort = (query, options) => {
  const cleanQuery = clean(query);

  return options
    .map(cleanseOption)
    .map((option) => addWeightWithBoost(option, cleanQuery))
    .filter(hasWeight)
    .sort(byWeightThenAlphabetically)
    .map(optionName);
};

export const suggestion = (value, options) => {
  const option = options.find((o) => o.name === value);
  if (option) {
    const html = option.append
      ? `<span>${value}</span> ${option.append}`
      : `<span>${value}</span>`;
    return option.hint ? `${html}<br>${option.hint}` : html;
  } else {
    return `<span>No results found</span>`;
  }
};

export const enhanceOption = (option) => {
  return {
    name: option.label,
    synonyms: option.getAttribute("data-synonyms")
      ? option.getAttribute("data-synonyms").split("|")
      : [],
    append: option.getAttribute("data-append"),
    hint: option.getAttribute("data-hint"),
    boost: parseFloat(option.getAttribute("data-boost")) || 1,
  };
};