API Reference

ChangeHook

ChangeHook is an optional callback on IExpression that receives the changed expression and previous value.

Source: expressions/expression-parser.interface.ts

IExpression

Description

Called after an expression value changes. Use it for local side effects tied to one expression instance.

Parameters

expressionIExpression

Expression instance that changed.

oldValueunknown

Value before the update.

Return type

void

API

export type ChangeHook = (expression: IExpression, oldValue: unknown) => void;

Usage example

import { rsx, type ChangeHook } from '@rs-x/expression-parser';

const expression = rsx<number>('a + b')({ a: 1, b: 2 });

const hook: ChangeHook = (changedExpression, oldValue) => {
  console.log('old:', oldValue);
  console.log('new:', changedExpression.value);
};

expression.changeHook = hook;