How to Conduct Testing Using React Hooks?

Hooks can help you extract the stateful logic from React components so the tester can test each component independently. With this state, the developer can reuse that component even without changing the component hierarchy. This allows multiple components to use the same Hooks.

Also, with Hooks, you can split the components into smaller pieces of code as per their interrelation. Contrary to splitting the same component can be used in a smaller function based on the lifecycle method.

When you pass the useeffect() function, React remembers that your component should perform a function after render. Once the DOM has been updated, React will call the function you passed. This useeffect() function can get used to performing multiple operations such as fetching data or calling imperative APIs, or even the timer feature.

In every React function, Hooks should get used at the top level. Avoid calling Hooks inside nested functions such as loops and conditions. If you follow this rule, Hooks will always be called in the same order when a component is rendered. Using this technique, React maintains the Hook state across multiple useStates and useEffects.

Following are the React Hooks you can use in your next application.

1. useState

Using this hook, you can create a state variable in your React function component.

1. useEffect

By using useEffect, we can perform side effects within function components.

1. useRef

It enables us to create a reference to a defined element/component when the component mounts.

1. useCallback

The UseCallback hook improves component performance.

1. useMemo

This method helps improve performance, just like useCallback, but instead of storing callback results, it stores memory.

1. useContext

When using React, we want to avoid the problem of creating multiple props for passing down data from one component to another. At that time, we can go for useContext.

1. useReducer

The useReducer hook manages a state similar to the useState hook, but it relies on the reducer function.

Although you can use Hooks, they are optional and 100% backward-compatible. This indicates that if you add or refactor your classes, you will not experience any breaking changes.

Furthermore, Hooks allows you to use React's local state feature without any need to write a class. In function components, Hooks provide access to React state and lifecycle features.

Apart from that, the use of hooks avoids scenarios such as HOC and renderProps to restructure your application with multiple hierarchies, resulting in a more readable and maintainable code base.

No. If you try to use the useState() Hook inside the condition or after some conditional statements, that can return a value. The program will throw a "React hook 'useState' is called conditionally" error. To solve such an error, try to move all Hooks outside the conditional statements.