naive effect implementation

effect.ts

type ClearEffectFN = (() => void) | undefined;
type EffectFN = (...args: any[]) => ClearEffectFN;

function effect(fn: EffectFN) {
  let prevParams: any[] | undefined = undefined;
  let clearFN: ClearEffectFN = undefined;
  return (...params: any[]) => {
    if (prevParams === undefined || isChanged(prevParams, params)) {
      if (typeof clearFN === 'function') {
        clearFN();
      }
      clearFN = fn(...params);
    }
    prevParams = params;
  }
}

function isChanged(prevParams: any[], currentParams: any[]) {
  let isChanged = false;
  prevParams.forEach((param, index) => {
    if (param !== currentParams[index]) {
      isChanged = true;
    }
  });
  return isChanged;
}