CODEWITHSUNDEEP
angularangular-signals
tlt
tlt

Reputation: 15271

Ignore initial run of effect()

we have:

effect(() => {
  console.log(`Value is ${newValue()}`);
});

We don't want whole console.log to run on initial signal set. We want it to run only starting with 2nd change of the signal.

Should we have a private field initialRun (true initially) in our component and set it to false at the end of our effect() code so that each subsequent run actually executes !initialRun && console.log(....)?

Or is there any smarter way?

Upvotes: 7

Views: 2469

Answers (1)

raphinesse
raphinesse

Reputation: 21048

According to https://github.com/angular/angular/issues/54372 there does not seem to be a built-in way to ignore the first run. But you should not need a private field either. A local variable should suffice (closures FTW):

constructor() {
  let initialRun = true;

  effect(() => {
    // Also read the signal the first time to setup the reactive dependency
    const value = newValue();
    
    if (!initialRun) {
      console.log(`Value is ${value}`);
    }
    
    initialRun = false;
  });
}

Upvotes: 1

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