Does WordPress have some hook when we open editor?

Question

I am wondering is there some kind of hook when we open post/page editor in WordPress? I want to make a function which will grab the content from the editor and add some pieces of code in to it automatically.

Answer 1

You can set the default editor content or change current content using "the_editor_content" filter.

Ex: set default editor content for "Add new" post.

add_filter( 'the_editor_content', 'set_default_editor_content', 1000, 2 );

function set_default_editor_content( $content, $default_editor ) {
        global $pagenow;
        if ( 'post-new.php' === $pagenow ) {
            ob_start();
            ?><p>Default content here...</p><?php
            return ob_get_clean();
        }
        return $content;
    }