Angular · Middle · Question 37 of 75

How do async validators behave in Angular forms?

✓Correct answer: They run after all sync validators pass; the control is PENDING while they run
2They replace sync validators completely
3They run on every keystroke regardless of sync errors

Explanation

Typical use is checking whether a username is taken. Combine with updateOn: 'blur' or debouncing in the validator to avoid a request per keystroke.

Further reading

Angular: Validating form input ↗

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