computed/extendedComputed

computed / extendedComputed is an extension of Angular’s computed. The main difference is extendedComputed callback is invoked with the previously computed value. This providers better DX for cases where the consumers need conditional computed and the result should have the previously computed value when a condition does not pass.

import { computed } from 'ngxtension/computed';
// or import { extendedComputed } from 'ngxtension/computed';

Usage

import { extendedComputed } from 'ngxtension/computed';

const multiplier = signal(2);
const count = signal(1);

const result = extendedComputed<number>((previousValue) => {
  // only compute when multiplier is even
  if (multiplier() % 2 === 0) {
    return count() * multiplier();
  }
  return previousValue;
});

result(); // 2

multiplier.set(3); // odd number
result(); // 2, previous value

multiplier.set(4);
result(); // 4