Android & React-Native Example

What is useMemo ? useMemo is a hook in react-native that will return the memorized value.  The most common advantage to use the useMemo is to optimize the performance of the react-native application. How it works? The useMemo will takes two arguments. In the first argument, you have to pass the function and in the second argument, you have to pass the array of dependencies.  useMemo will recompute the memorized values once one of the dependencies has changed. Whenever the state is changed in the react-native the component re-render itself. In react-native some-times, we have functions that have expensive calculations code. Once the state has updated the react-native component will call the render and the function will be called again and do the calculation even if the state has no effect on that method. Using useMemo we can resolve the above issue. Impact of useMemo in application performance Using useMemo you can avoid expensive calculations on every render, Which will h...

What is useState? In react-native props and state are the data which are used to handle the component. The component will update itself as soon as the state changes its value.  useState is a hook that is used to define the state for the functional component. Using useState you can define the initial value for the state and update it later for the functional component. How to use useState? import React, {  useState } from 'react'; const [loading, setLoading] = useState(true);   The above is the syntax to define and used the hook in the functional component. We have defined the initial value is true for the above state. loading : The name of the state. setLoading : Method definition to update the value of the state later in the code. useState : Define the const to work as the state and pass the initial value to it. How to update the value for the useState? To update the state value you can see the setLoading method defined in the example. setLoading(false)   ...

What is useEffect :   In our application, we required to call network operations, subscription for the events, etc. The useEffect provides you a way to handle that operation using hooks. The useEffect is a combination of lifecycle methods of the react component and provides you a better way to handle those events. The useEffect is a combination of lifecycle methods  componentDidMount , componentDidUpdate , and componentWillUnmount . Now, let's start with how can we define and use the useEffect in react-native. Syntax of useEffect  To use the useEffect you required to import it from the react package. import React, { useState, useEffect } from 'react'; useEffect(()=>{ }) or   React.useEffect(()=>{ }) How useEffect works? The useEffect is called after every render.  After the first render takes the place the useEffect will be call and perform the operations. It will affect the performance of the application but we have some ways using which we can custo...