Get a page´s content with alias by using the $_GET method?

<?php
return $_GET['pageID'];

<?php
if (!isset ($pageID))  {
	return "The page with the requested id does not exist!";
}
else {
	$res = $modx->getObject('modResource', $pageID);
	return ($res->get('content'));
}

[[!PageCall? &pageID=`[[!GetPageId]]`]]

$docArray = $modx->getObject('modResource',array( 
'published' => 1,
'alias' => 'first-page',
'published' => 1,
'alias' => 'second-page',
));
return ($docArray->get('content'));

$modx->getObject('modResource', array('alias' => $_GET['pageAlias'));

$pages = array("Page1", "Page2", "Page3");
if (in_array("Page1", $pages)) {
    return ($modx->get('content'));
}
else{
return "That page does not exist within this section!";
}

$res = $modx->getObject('modResource', array(
'alias' => $_GET['pageAlias']
));
if(isset($res['alias']['example-page'])){
    return ($modx->get('content'));
}
elseif(!isset($res['alias']['example-page'])){
return "That page does not exist within this section!";
}
}

<?php
$legalAliases = explode(',' , $scriptProperties['legalAliases']);
 
if (in_array($_GET['pageAlias'], $legalAliases, true) ) {
    $res = $modx->getObject('modResource', array(
'alias' => $_GET['pageAlias']));
        
    if ($res) {
        return $res->getContent();
    } else {
       return 'Resource not found';
    }
} else {
    return "That page does not exist within this section!";
}

$res = $modx->getObject('modResource',array(
'alias' => $_GET['pageAlias']
));
$actions = explode(",", $scriptProperties['actions']);

if(in_array($_GET['pageAlias'],$actions)){
    return ($res->get('content'));
    }
    else
    {
    echo "That page does not exist within this section!";
    }

<?php

$actions = explode(",", $scriptProperties['actions']);

if (in_array($_GET['pageAlias'], $actions)) {

    $res = $modx->getObject('modResource', array(
        'alias' => $_GET['pageAlias']
    ));

    if (!$res) {
        return 'Resource not found';
    } else {
        return ($res->get('content'));
    }
} else {
    echo "That page does not exist within this section!";
}