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React Functional Components Lifecycle Methods.

march 15, 2024
5 minutes read
By DI Solutions
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React Lifecycle Methods in Functional Components

React applications are composed of different independent components as we have learned. Every component has its own lifecycle. A lifecycle of a component is a different set of methods which are invoked by different component’s execution phases. We can only have the lifecycle method in the class components, the functional components but the hooks used in functional components and follow the ES6 practices when you hire more advanced react developers.

Basically, the life cycle of components contains 4 different phases.

1. Initialization

During this phase, the developer has the job of defining all the props and the initial state which will be used in the component.
Usually, this is done in the component’s constructor.

class abc extends React.Component { constructor(props){
this.data = { dates : new Date() };}}

2. Mounting

This is how the component life cycle unfolds: the props and the states are fixed by the time the component is created.

This next step is going to be the mounting of the component in DOM which will be rendered for the first time on the website’s page.

There are simple rules for Naming optimization in React.

But only after we have a complete understanding of how the application should function can we effectively separate out the roles.

Here there are two functions written above in which the words will mean before the occurrence of a certain phase and would mean after the occurrence of that phase.

The mounting phase has two functions which are described below.

componentWillMount() Function

  • As the name clearly suggests, this function will always be called before the component is rendered for the first time.

componentDidMount() Function

  • Similarly, as per name says, this function will always be called after the components are rendered on the web page.

3. Updation

We can work with React js lib and make active web pages which means that these web pages are the ones which if the user uses them will react to their actions.

Consider the Online IDE webpage, for the sake of this page we can call it act like its master.

At the same time, a Light Theme code could as well be written by Ram and a Dark Theme code by another User in Python.

This avatar of a web site is called interactive web page, there the web site behavior is based on user.

Probably, you will be anxious why the instance shown above is related to updation!

Therefore, the implication is evident in the name; this is the stage where all the already defined props and states are updated as required when events such as clicking, pressing a key on the keyboard, etc. take place.

The Updation phase is an executing process that involves call at different times of its functions. Their specifications are given as below.

The model has 5 phases, the details regarding the phases follows below.

componentWillReceiveProps() Function

  • The function of single neurons is always independent of any previous condition (state-independent).

Mounting is the name of this function, which is invoked just before the props are assigned to the component which has just been mounted.

This changes the function that passes down the props and states (which may or may not be similar to the previous props and states)

A scenario is illustrated in the code snippet shown here.


if (this.props !== newProps) {
console.log(“New Props … “);

setState() Function

5. That is not, however, among the list of the life cycle

We can apply this purpose also implicitly.

This operation is for updating.

shouldComponentUpdate() Function

Each state and prop will have a replication on the webpage, but there are some cases where the result might be the opposite.

In react namespace, the duty of the function shouldComponentUpdate() is to determine whether the output of the component will be influenced or not.

This method is normally called earlier than the mounting process of the component when at the time of the arrival of some fresh data by a user.

If the function produces a false value then the step of rendering the component wouldn’t be executed.

It is also used to check whether the piece should be rendered or not on the basis of upcoming properties.

componentWillUpdate() Function:

It is naming that gives the next function its fame. This function will always be executed before the component gets rendered.

A single call to this function is just before writing the server's response.

When the nextProps or nextState gets updated the function runs.

componentDidUpdate() Function

Just like that, this function is called or invoked once components are re-rendered.

This function is the exact opposite of the componentWillUpdate()function as it is invoked only after the updates of props and states.

4. Unmounting

Unmounting is the final stage/phase of the entire lifecycle of the component.

Mentioned below is the only function.

componentWillUnmount() Function

The function is run after the component gets mounted from DOM but before it gets unmounted.

After the function completes being invoked the lifecycle enters the un-mounted stage.

So, as we have mentioned till we perform to reach the life cycles and prestructured functions which require studying.hire Dedicated Reactjs developersat DI Solutions to get the most Outperformed Results.