Address Autocomplete Fundamentals

Address autocomplete improves user experience by suggesting addresses as users type, reducing errors and speeding up form completion.

Why Autocomplete?

Key Components

1. Debouncing

Don't query on every keystroke - wait for user to pause:

javascript
1function debounce(fn, delay) {
2  let timeout;
3  return (...args) => {
4    clearTimeout(timeout);
5    timeout = setTimeout(() => fn(...args), delay);
6  };
7}
8
9const debouncedSearch = debounce(searchAddresses, 300);
10
11// Now: debouncedSearch('123 Mai')
12// Waits 300ms before calling API

2. Minimum Characters

Don't search until enough input:

javascript
1async function getSuggestions(query) {
2  if (query.length < 3) return [];  // Too short
3  return await searchAPI(query);
4}

3. Caching

Cache results to avoid repeated API calls:

javascript
1const cache = new Map();
2
3async function getCachedSuggestions(query) {
4  if (cache.has(query)) return cache.get(query);
5
6  const results = await searchAPI(query);
7  cache.set(query, results);
8  return results;
9}

Using Nominatim for Autocomplete

javascript
1async function searchAddresses(query) {
2  const params = new URLSearchParams({
3    q: query,
4    format: 'json',
5    addressdetails: '1',
6    limit: '5',
7    countrycodes: 'us'  // Limit to US
8  });
9
10  const response = await fetch(
11    `https://nominatim.openstreetmap.org/search?${params}`,
12    { headers: { 'User-Agent': 'MyApp/1.0' } }
13  );
14
15  return response.json();
16}

Best Practices

1. Debounce 200-400ms - Balance responsiveness and API usage
2. Minimum 3 characters - Avoid too many irrelevant results
3. Limit results to 5-10 - Don't overwhelm users
4. Show loading state - Indicate search in progress
5. Handle errors gracefully - Don't break form on API failure
6. Keyboard navigation - Allow arrow keys to select