Scalar functions
Create row-by-row transformations and calculations in JavaScript.
Programmable SQLite
Create custom SQLite functions in JavaScript.
Extend SQLite with scalar functions, aggregates, window functions, collations, and JavaScript evaluation.
SQLite-JS
SQLite-native extension
Best for
Custom SQL functions and logic
Repository
GitHubProject
What it is
SQLite-JS embeds JavaScript into SQLite so developers can define reusable database logic with familiar code and call it from SQL.
It is useful when application behavior, transformations, scoring, validation, or custom ordering need to travel with the local database rather than live in one backend service.
Why it matters
Push logic
to the edge.
Edge and offline-first apps need local business logic as much as local data. SQLite-JS lets you ship that logic inside the database runtime.
When paired with SQLite Sync, function definitions can be distributed to clients so the same behavior is available across devices and agents.
Capabilities
Features and characteristics
Aggregate functions
Compute grouped results such as custom medians, scores, or reducers.
Window functions
Use JavaScript logic over SQL windows without collapsing result rows.
Collations
Define custom text ordering for application-specific sorting.
JavaScript evaluation
Evaluate JavaScript snippets from SQL for flexible embedded computation.
Multi-runtime packages
Use native builds plus Swift, Android, Node.js, Flutter, and Dart packages.
Sample code
Define a JavaScript function and query it
Register custom JavaScript once, then use it like any other SQLite function.
-- Load SQLite-JS
.load ./js
SELECT js_create_scalar('age', '(function(args) {
const birthDate = new Date(args[0]);
const today = new Date();
let age = today.getFullYear() - birthDate.getFullYear();
const m = today.getMonth() - birthDate.getMonth();
if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {
age--;
}
return age;
})');
SELECT name, age(birth_date) AS age
FROM people;