wp-admin/includes/class-custom-image-header.php:355Executes JavaScript depending on step.
public function js() { $step = $this->step(); if ( ( 1 === $step || 3 === $step ) && current_theme_supports( 'custom-header', 'header-text' ) ) { $this->js_1(); } elseif ( 2 === $step ) { $this->js_2(); } }Introduced in 2.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-custom-image-header.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.