@livefolio/sdk / defineFeature

Function: defineFeature()

defineFeature<K>(kind, compute): void

Defined in: features/spec.ts:82

Registers a compute function for a new or existing feature kind.

Throws if kind is already registered. Call this once at module initialisation time (top-level) to extend the built-in feature registry with custom indicators. The compute function receives the raw price Series and the full typed spec object for that kind; it must return a Series of the same or shorter length.

Type Parameters

Type Parameter
K extends "price" | "sma" | "ema" | "rsi" | "return" | "volatility" | "drawdown"

Parameters

Parameter	Type	Description
kind	K	The FeatureKind string that identifies this indicator.
compute	(series, spec) => Series	Pure function that transforms a price series according to spec. The spec argument is narrowed to Extract<FeatureSpec, { kind: K }> so TypeScript enforces that only the correct parameter shape is accessed.

Returns

void

void. Registration is a side-effectful, one-time operation.

Example

import { defineFeature } from '@livefolio/sdk';

// Register a custom 'zscore' feature kind
defineFeature('sma', (series, spec) => {
  // Already built-in; this would throw due to duplicate registration.
  // Shown here for illustration only.
  return series;
});