need code to select page

You should read the code of Twenty Seventeen. https://www.ads-software.com/themes/twentyseventeen/
It has a Customizer option for the front page to allow you to choose which Pages to show.

OK. thanks

I copied below from somewhere and applied it in my plugin and gives exactly what I want.
The problem right now is that though it selects pages but doesn’t save the chosen page. what should I add to it.

<select name=”easyreg_redirect_page”>
<option selected=”selected” value=”0″><?php echo esc_attr( __( ‘Select page’ ) ); ?></option>
<?php
$selected_page = get_option( ‘option_key’ );
$pages = get_pages();
foreach ( $pages as $page ) {
$option = ‘<option value=”‘ . $page->ID . ‘” ‘;
$option .= ( $page->ID == $selected_page ) ? ‘selected=”selected”‘ : ”;
$option .= ‘>’;
$option .= $page->post_title;
$option .= ‘</option>’;
echo $option;
}
?>
</select>

It is easy to show a dropdown list of pages. It’s even easier when you use the WP function for it: https://developer.www.ads-software.com/reference/functions/wp_dropdown_pages/

The problem with copying that code is that showing the list is the only thing it does. Saving the choice is different if it’s in the Customizer or the editor or an options page. The Customizer is probably easiest; that’s why I suggested you look at Twenty Seventeen. The Customizer does the saving for you. You just have to initialize with the option name and default value. Then do the rendering according to the saved value.

ok. This is what i could see in the customizer.php as you have pointed out. I concern is that as i am using it in wordpress plugin for my widget area, how do i use this function then to execute dropdown page list for selection
/**
* Filter number of front page sections in Twenty Seventeen.
*
* @since Twenty Seventeen 1.0
*
* @param int $num_sections Number of front page sections.
*/
$num_sections = apply_filters( ‘twentyseventeen_front_page_sections’, 4 );

// Create a setting and control for each of the sections available in the theme.
for ( $i = 1; $i < ( 1 + $num_sections ); $i++ ) {
$wp_customize->add_setting(
‘panel_’ . $i,
array(
‘default’ => false,
‘sanitize_callback’ => ‘absint’,
‘transport’ => ‘postMessage’,
)
);

$wp_customize->add_control(
‘panel_’ . $i,
array(
/* translators: %d: The front page section number. */
‘label’ => sprintf( __( ‘Front Page Section %d Content’, ‘twentyseventeen’ ), $i ),
‘description’ => ( 1 !== $i ? ” : __( ‘Select pages to feature in each area from the dropdowns. Add an image to a section by setting a featured image in the page editor. Empty sections will not be displayed.’, ‘twentyseventeen’ ) ),
‘section’ => ‘theme_options’,
‘type’ => ‘dropdown-pages’,
‘allow_addition’ => true,
‘active_callback’ => ‘twentyseventeen_is_static_front_page’,
)
);

$wp_customize->selective_refresh->add_partial(
‘panel_’ . $i,
array(
‘selector’ => ‘#panel’ . $i,
‘render_callback’ => ‘twentyseventeen_front_page_section’,
‘container_inclusive’ => true,
)
);
}
}
add_action( ‘customize_register’, ‘twentyseventeen_customize_register’ );

OK, a plugin could have a widget (with its own interface which has to work in the widget page and in the Customizer) or a meta box in the editor, or a block, or a button on the Classic editor toolbar, or an options page, or a Customizer section.
But you can’t just take code written for one environment and use it in another. They are all different for how you save the options and any needed Javascript.
Using the options once they are saved is different if it’s in a widget than in a normal option or in post meta.

If you are set on a widget, you only need to select one Page and then the user can add as many of those widgets as they want. Widget options are in the options table, but the code to handle them is within the Widget class that your code extends. Take a look at the core Pages widget to see, although it might not have any options.

Below is what I have done for category list and how do I change or amend this to display pages

<p>
<label for=”<?php echo $this->get_field_id(‘cat_id’); ?>”><?php _e( ‘Category Name:’ , ‘bav_itp’)?></label>
<select id=”<?php echo $this->get_field_id(‘cat_id’); ?>” name=”<?php echo $this->get_field_name(‘cat_id’); ?>”>
<option value=”0″>Choose category:</option>
<?php
$this->categories = get_categories();
foreach ( $this->categories as $cat ) {
$selected = ( $cat->term_id == esc_attr( $cat_id ) ) ? ‘ selected = “selected” ‘ : ”;
$option = ‘<option ‘.$selected .’value=”‘ . $cat->term_id;
$option = $option .'”>’;
$option = $option .$cat->name;
$option = $option .'</option>’;
echo $option;
}
?>
</select>
</p>