API Reference

IExpression

Core runtime representation of a bound expression. Read current value from value and listen for updates through changed.

rsx function

Description

value contains the current computed result.

changed emits when tracked dependencies change and the expression re-evaluates.

Parameters

Tgeneric type parameter

Current expression value type.

PTgeneric type parameter

Parent expression value type.

Return type

Type contract only. Runtime bindings return an IExpression<T> instance.

Usage notes

Use parent, childExpressions, type, and isRoot to inspect expression structure.

type uses ExpressionType.

changeHook uses ChangeHook.

Lifecycle

IExpression is disposable. Call dispose() when you no longer need it.

API

export interface IExpression<T = unknown, PT = unknown> extends IDisposable {
  readonly id: string;
  readonly changed: Observable<IExpression>;
  readonly type: ExpressionType; // see /docs/expression-type
  readonly expressionString: string;
  readonly parent: IExpression<PT> | undefined;
  readonly childExpressions: readonly IExpression[];
  readonly value: T | undefined;
  readonly isRoot: boolean;
  readonly isAsync: boolean | undefined;
  readonly hidden: boolean;
  changeHook?: ChangeHook; // see /docs/change-hook
  toString(): string;
  clone(): this;
  bind(settings: IExpressionBindConfiguration): IExpression;
}

Usage example

import { InjectionContainer } from '@rs-x/core';
import { rsx, RsXExpressionParserModule, type IExpression } from '@rs-x/expression-parser';

await InjectionContainer.load(RsXExpressionParserModule);

const model = { a: 10, b: 20 };
const expression: IExpression<number> = rsx<number>('a + b')(model);

console.log(expression.value); // current value

expression.changed.subscribe(() => {
  console.log(expression.value); // updated value
});