I am trying to write a widget and I need to add the color picker to my widget form. I want to add the script only on widget.php page and not on all the admin pages.
Is there a way that I can detect the page inside the construct function of my widget? If not how I can include the script only when I'm on widget.php page?
You may use the global variable $pagenow to figure out if you are on a particular admin page, in your case this would be checking if you are on the widgets.php admin page:
<?php
global $pagenow;
if( $pagenow === 'widgets.php' ) {
?>
<script>
// JavaScript goes here
</script>
<?php
}
Furthermore, it will be helpful for you to use the plugin Query Monitor so that you may easily find out what conditionals may be used on a particular instance.
$GLOBALS['pagenow'], which has the benefit of fitting into one line, no need to declare the global access on a separate line.