IndexedDB is a powerful web API for storing and querying large amounts of structured data in web browsers. It provides a key-value store where data is indexed for efficient retrieval. While IndexedDB offers excellent performance for retrieving data by key, it lacks built-in support for full-text search. However, with some extra effort, it is possible to implement full-text search in IndexedDB. In this blog post, we will explore how to achieve this using JavaScript.

The Challenge

The main challenge in implementing full-text search in IndexedDB is that it does not directly support searching for specific words within a value. Instead, we need to manually extract the words from the value and create our own search index.

Creating a Search Index

To create a search index, we need to tokenize the text by splitting it into individual words and storing them alongside the corresponding record. We can achieve this by preprocessing the data before storing it in IndexedDB.

function createIndex(text) {
  const words = text.split(' ');
  const index = {};

  for (let i = 0; i < words.length; i++) {
    const word = words[i].toLowerCase();
    index[word] = true;
  }

  return index;
}

In the createIndex function above, we split the text into individual words, convert them to lowercase, and store them as keys in an object. This object serves as our search index. We can then store this index alongside the actual data in IndexedDB.

Performing a Full-Text Search

To perform a full-text search, we need to retrieve the search index from the IndexedDB and match the query against the stored words. Here’s an example implementation:

function search(query) {
  const indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB;
  const request = indexedDB.open('database', 1);

  request.onsuccess = (event) => {
    const db = event.target.result;
    const transaction = db.transaction('data', 'readonly');
    const objectStore = transaction.objectStore('data');

    objectStore.openCursor().onsuccess = (event) => {
      const cursor = event.target.result;

      if (cursor) {
        const index = cursor.value.index;
        const words = Object.keys(index);

        if (words.includes(query.toLowerCase())) {
          // Match found!
          console.log('Matching record:', cursor.value.data);
        }

        cursor.continue();
      }
    };
  };
}

In the search function above, we open a transaction to read data from the IndexedDB object store named ‘data’. We then iterate over each record, retrieve the search index, and check if the query matches any of the words in the index. If a match is found, we can take the desired action, such as logging the matching record.

Conclusion

Implementing full-text search in IndexedDB requires manual indexing of the data and querying the index to retrieve matching records. By following the steps outlined in this blog post, you can enable powerful full-text search capabilities within your web applications. Remember to preprocess your data and create a search index to improve search performance. Happy searching!

#indexedDB #fulltextsearch