A PHP Error was encountered

Severity: 8192

Message: Return type of CI_Session_files_driver::open($save_path, $name) should either be compatible with SessionHandlerInterface::open(string $path, string $name): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice

Filename: drivers/Session_files_driver.php

Line Number: 132

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: 8192

Message: Return type of CI_Session_files_driver::close() should either be compatible with SessionHandlerInterface::close(): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice

Filename: drivers/Session_files_driver.php

Line Number: 292

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: 8192

Message: Return type of CI_Session_files_driver::read($session_id) should either be compatible with SessionHandlerInterface::read(string $id): string|false, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice

Filename: drivers/Session_files_driver.php

Line Number: 166

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: 8192

Message: Return type of CI_Session_files_driver::write($session_id, $session_data) should either be compatible with SessionHandlerInterface::write(string $id, string $data): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice

Filename: drivers/Session_files_driver.php

Line Number: 235

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: 8192

Message: Return type of CI_Session_files_driver::destroy($session_id) should either be compatible with SessionHandlerInterface::destroy(string $id): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice

Filename: drivers/Session_files_driver.php

Line Number: 315

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: 8192

Message: Return type of CI_Session_files_driver::gc($maxlifetime) should either be compatible with SessionHandlerInterface::gc(int $max_lifetime): int|false, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice

Filename: drivers/Session_files_driver.php

Line Number: 356

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: ini_set(): Session ini settings cannot be changed after headers have already been sent

Filename: Session/Session.php

Line Number: 282

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: session_set_cookie_params(): Session cookie parameters cannot be changed after headers have already been sent

Filename: Session/Session.php

Line Number: 294

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: ini_set(): Session ini settings cannot be changed after headers have already been sent

Filename: Session/Session.php

Line Number: 304

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: ini_set(): Session ini settings cannot be changed after headers have already been sent

Filename: Session/Session.php

Line Number: 314

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: ini_set(): Session ini settings cannot be changed after headers have already been sent

Filename: Session/Session.php

Line Number: 315

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: ini_set(): Session ini settings cannot be changed after headers have already been sent

Filename: Session/Session.php

Line Number: 316

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: ini_set(): Session ini settings cannot be changed after headers have already been sent

Filename: Session/Session.php

Line Number: 317

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: ini_set(): Session ini settings cannot be changed after headers have already been sent

Filename: Session/Session.php

Line Number: 375

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: session_set_save_handler(): Session save handler cannot be changed after headers have already been sent

Filename: Session/Session.php

Line Number: 110

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

A PHP Error was encountered

Severity: Warning

Message: session_start(): Session cannot be started after headers have already been sent

Filename: Session/Session.php

Line Number: 143

Backtrace:

File: /home/infovistar/public_html/application/controllers/reactjs/Reactjs.php
Line: 7
Function: __construct

File: /home/infovistar/public_html/index.php
Line: 315
Function: require_once

React for Beginners | Lists and Keys
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React for Beginners | Lists and Keys

Iterate over arrays in JSX using map

  • How do we displays lists in JSX using array data?
  • Use the .map() function to convert lists of data (arrays) into lists of elements,
const people = ["Junaid", "Aadil", "Musaddik"];
const peopleList = people.map((person) => <p>{person}</p>);
map() can be used for components as well as plain JSX elements.
function App() {
    const people = ["Junaid", "Aadil", "Musaddik"];

    return (
        <ul>
            {
                people.map((person) => {
                    <Person name={person} />
                })
            }
        </ul>
    );
}

function Person({name}) {
    // We access the 'name' prop directly using object destructuring 
    return <p>This person's name is : {name}</p>;
}

The importance of keys in lists

  • Each React element within a list of elements needs a special key prop
  • Keys are essential for React to be able to keep track of each element that is beeing iterated over with the .map() function
  • React uses keys to performantly update individual elements when their data changes (instead of re-rendering the entire list)
  • Keys need to have unique values to be able to identify each of them according to their key value
function App() {
	const people = [
		{ id : "Ksy7py", name : "Junaid" },
		{ id : "6eAdl9", name : "Aadil" },
		{ id : "6eAde9", name : "Musaddik" },
	];

	return (
		<ul>
			{
				people.map((person) => (
					<Person key={person.id} name={person.name} />
				))
			}
		</ul>
	);
}