useMemo 与 React.memo 与 pureComponent

Question

There are many ways to do one thing in react nowadays. Take memo for example, what's the difference between useMemo and memo(MyComponent) and React.PureComponent ? Aren't they're doing the same thing? so which one we should use today? If we judge base on the date of the newer API we should use useMemo ?

Answer 1

We can use useMemo and React.memo inside the functional component

• React.memo: Used to memoize components.

Suppose you have two components , two of which are on the same level , and the other component is the parent of these two components. We pass our states from the parent component to the children. When a change is made to one of the child components, the other child component is re-rendered . React.memo is used to prevent this re-rendering.

• React.useMemo: Used to memoize value

When our calculations are allowed in an over function, this function is rendered with each re-rendering of the component. Using useMemo , we set the useMemo to be re-rendered only in certain cases