Design Patterns · Senior · Question 57 of 75

What does "parse, don't validate" mean?

✓Correct answer: Turn untrusted input into a more precise type once at the boundary, so the rest of the code can't receive invalid data
2Never validate user input
3Use JSON.parse instead of schemas

Explanation

A validator returning boolean loses information; a parser returning Email or an error keeps the proof in the type.

Further reading

Test yourself

Take the Design Patterns · Senior quiz: questions and options are shuffled, and you get a review of your mistakes at the end.