What types of values can useState hold?

The useState hook accepts different types of values.

• Primitives: number, string, boolean
• Arrays
• Objects
• Functions
• null or undefined

But you needs to be cautious with reference types (objects/arrays) because React compares old and new values by reference, so direct mutations won't trigger a re-render. For example, the correct and wrong ways of state updates as shown below,

user.name = "Alex"; //wrong way
setUser(prev => ({ ...prev, name: 'Alex' })); //correct way