master/number_8php_source.html

 <?php
 $vars['class'] = elgg_extract_class($vars, 'elgg-input-number');

 $defaults = [
     'type' => 'number',
 ];

 $vars = array_merge($defaults, $vars);

 echo elgg_format_element('input', $vars);
$vars
$vars['class']
Elgg number input Displays a number input field.
Definition: number.php:9

$defaults
$defaults
Definition: number.php:11

elgg_format_element
elgg_format_element(string $tag_name, array $attributes=[], string $text= '', array $options=[])
Format an HTML element.
Definition: output.php:145

elgg_extract_class
elgg_extract_class(array $array, array|string $existing=[], string $extract_key= 'class')
Extract class names from an array, optionally merging into a preexisting set.
Definition: elgglib.php:277