After a certain component complexity or with a certain dependency graph, memoizing functions can be a huge performance win, but there are also cases where it just leads to unnecessarily complex code and sometimes even worse performance. React Memo is one of the most useful tools when it comes to optimizing the performance of your React components. A hook like useStyle or useMemo also comes with a cost (allocating the function and the deps array, calling the actual hook and running an array comparison), so keep in mind that it is often better to just pass in objects or arrays directly if the component itself is optimized. the useStyle one) are very small and only demonstrate the idea. If your app feels slow, try the react-native-performance library and it's flipper plugin to profile your app's performance in various aspects such as time to interactive, component render time, script execution and more.ĭon't prematurely optimize. See the official docs for mo, and use mo(.) wisely. This means that React will skip rendering the component, and reuse the last rendered result. If your component renders the same result given the same props, you can wrap it in a call to mo(.) for a performance boost in some cases by memoizing the result. Numbers, strings and booleans are value types, which means they can be compared by value:Ĭonst o1 = export const M圜omponent = React. When a pure component re-renders, it compares the previous props to the current props and checks if they are shallow-equal. Often those variables even go over the Bridge and make your app slow. The Memo API avoids unnecessary re-renders in functional components and thereby optimizing the performance of the application. As the name suggests, Memo API uses the memoization technique to optimize performance and makes the application faster. mo() React 16.6.0 mo() React. When you pass those variables down to pure components via props, they will still re-render even though the props are logically the same. React memo is a Higher Order Component (HOC) introduced in React v16.6. While this is not a problem for value types, this causes reference types to be different on every render. Pure ComponentsĪ Pure Component (or a mo component) does not re-render if it's props are shallow equal.Įach variable you create in your render function will get re-allocated on each render. You don't want to run a lot of operations in those renders for very obvious reasons - so no heavy filtering, no list operations, etc. A re-render occurs when state changes, redux dispatches some action, or when the user types into a text input (re-render for every single key press). It's important to memoize heavy computations as well as arrays and object creations so that they don't get re-created on every render. Returning the cached result when the same You can create your own function that would eventually support children and pass it to mo(M圜omp, m圜hildrenAwareEqual). The results of expensive function calls and mo by default just use simple shallow comparison so there really is no other direct way to solve it. Is an optimization technique used primarily
0 Comments
Leave a Reply. |