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TypeScript Quiz Practice
Active Recall Drill Session
← Exit Session
Question 1 of 1
medium
TypeScript
What is a 'type predicate' function?
A
Any function that returns a boolean
B
A function whose return type is written as `x is T` instead of plain boolean, which TypeScript uses to narrow the argument's type at call sites
C
A function that only works with primitives
D
A deprecated TypeScript feature
Check Answer